diff --git a/changelog.d/9154.feature b/changelog.d/9154.feature
new file mode 100644
index 0000000000..01a24dcf49
--- /dev/null
+++ b/changelog.d/9154.feature
@@ -0,0 +1 @@
+Add support for multiple SSO Identity Providers.
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index 7fdd798d70..b49a5da8cc 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -1726,6 +1726,10 @@ saml2_config:
 #   idp_name: A user-facing name for this identity provider, which is used to
 #       offer the user a choice of login mechanisms.
 #
+#   idp_icon: An optional icon for this identity provider, which is presented
+#       by identity picker pages. If given, must be an MXC URI of the format
+#       mxc://<server-name>/<media-id>
+#
 #   discover: set to 'false' to disable the use of the OIDC discovery mechanism
 #       to discover endpoints. Defaults to true.
 #
diff --git a/mypy.ini b/mypy.ini
index b996867121..bd99069c81 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -100,6 +100,7 @@ files =
   synapse/util/async_helpers.py,
   synapse/util/caches,
   synapse/util/metrics.py,
+  synapse/util/stringutils.py,
   tests/replication,
   tests/test_utils,
   tests/handlers/test_password_providers.py,
diff --git a/synapse/config/oidc_config.py b/synapse/config/oidc_config.py
index df55367434..f257fcd412 100644
--- a/synapse/config/oidc_config.py
+++ b/synapse/config/oidc_config.py
@@ -23,6 +23,7 @@ from synapse.config._util import validate_config
 from synapse.python_dependencies import DependencyException, check_requirements
 from synapse.types import Collection, JsonDict
 from synapse.util.module_loader import load_module
+from synapse.util.stringutils import parse_and_validate_mxc_uri
 
 from ._base import Config, ConfigError
 
@@ -66,6 +67,10 @@ class OIDCConfig(Config):
         #   idp_name: A user-facing name for this identity provider, which is used to
         #       offer the user a choice of login mechanisms.
         #
+        #   idp_icon: An optional icon for this identity provider, which is presented
+        #       by identity picker pages. If given, must be an MXC URI of the format
+        #       mxc://<server-name>/<media-id>
+        #
         #   discover: set to 'false' to disable the use of the OIDC discovery mechanism
         #       to discover endpoints. Defaults to true.
         #
@@ -207,6 +212,7 @@ OIDC_PROVIDER_CONFIG_SCHEMA = {
     "properties": {
         "idp_id": {"type": "string", "minLength": 1, "maxLength": 128},
         "idp_name": {"type": "string"},
+        "idp_icon": {"type": "string"},
         "discover": {"type": "boolean"},
         "issuer": {"type": "string"},
         "client_id": {"type": "string"},
@@ -336,9 +342,20 @@ def _parse_oidc_config_dict(
             config_path + ("idp_id",),
         )
 
+    # MSC2858 also specifies that the idp_icon must be a valid MXC uri
+    idp_icon = oidc_config.get("idp_icon")
+    if idp_icon is not None:
+        try:
+            parse_and_validate_mxc_uri(idp_icon)
+        except ValueError as e:
+            raise ConfigError(
+                "idp_icon must be a valid MXC URI", config_path + ("idp_icon",)
+            ) from e
+
     return OidcProviderConfig(
         idp_id=idp_id,
         idp_name=oidc_config.get("idp_name", "OIDC"),
+        idp_icon=idp_icon,
         discover=oidc_config.get("discover", True),
         issuer=oidc_config["issuer"],
         client_id=oidc_config["client_id"],
@@ -366,6 +383,9 @@ class OidcProviderConfig:
     # user-facing name for this identity provider.
     idp_name = attr.ib(type=str)
 
+    # Optional MXC URI for icon for this IdP.
+    idp_icon = attr.ib(type=Optional[str])
+
     # whether the OIDC discovery mechanism is used to discover endpoints
     discover = attr.ib(type=bool)
 
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 75ba161f35..47a0370173 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -26,7 +26,7 @@ import yaml
 from netaddr import IPSet
 
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
-from synapse.http.endpoint import parse_and_validate_server_name
+from synapse.util.stringutils import parse_and_validate_server_name
 
 from ._base import Config, ConfigError
 
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index e5339aca23..171d25c945 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -49,7 +49,6 @@ from synapse.events import EventBase
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.federation.persistence import TransactionActions
 from synapse.federation.units import Edu, Transaction
-from synapse.http.endpoint import parse_server_name
 from synapse.http.servlet import assert_params_in_dict
 from synapse.logging.context import (
     make_deferred_yieldable,
@@ -66,6 +65,7 @@ from synapse.types import JsonDict, get_domain_from_id
 from synapse.util import glob_to_regex, json_decoder, unwrapFirstError
 from synapse.util.async_helpers import Linearizer, concurrently_execute
 from synapse.util.caches.response_cache import ResponseCache
+from synapse.util.stringutils import parse_server_name
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index cfd094e58f..95c64510a9 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -28,7 +28,6 @@ from synapse.api.urls import (
     FEDERATION_V1_PREFIX,
     FEDERATION_V2_PREFIX,
 )
-from synapse.http.endpoint import parse_and_validate_server_name
 from synapse.http.server import JsonResource
 from synapse.http.servlet import (
     parse_boolean_from_args,
@@ -45,6 +44,7 @@ from synapse.logging.opentracing import (
 )
 from synapse.server import HomeServer
 from synapse.types import ThirdPartyInstanceID, get_domain_from_id
+from synapse.util.stringutils import parse_and_validate_server_name
 from synapse.util.versionstring import get_version_string
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/handlers/cas_handler.py b/synapse/handlers/cas_handler.py
index f3430c6713..0f342c607b 100644
--- a/synapse/handlers/cas_handler.py
+++ b/synapse/handlers/cas_handler.py
@@ -80,6 +80,10 @@ class CasHandler:
         # user-facing name of this auth provider
         self.idp_name = "CAS"
 
+        # we do not currently support icons for CAS auth, but this is required by
+        # the SsoIdentityProvider protocol type.
+        self.idp_icon = None
+
         self._sso_handler = hs.get_sso_handler()
 
         self._sso_handler.register_identity_provider(self)
diff --git a/synapse/handlers/oidc_handler.py b/synapse/handlers/oidc_handler.py
index ba686d74b2..1607e12935 100644
--- a/synapse/handlers/oidc_handler.py
+++ b/synapse/handlers/oidc_handler.py
@@ -271,6 +271,9 @@ class OidcProvider:
         # user-facing name of this auth provider
         self.idp_name = provider.idp_name
 
+        # MXC URI for icon for this auth provider
+        self.idp_icon = provider.idp_icon
+
         self._sso_handler = hs.get_sso_handler()
 
         self._sso_handler.register_identity_provider(self)
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 3bece6d668..ee27d99135 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -38,7 +38,6 @@ from synapse.api.filtering import Filter
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersion
 from synapse.events import EventBase
 from synapse.events.utils import copy_power_levels_contents
-from synapse.http.endpoint import parse_and_validate_server_name
 from synapse.storage.state import StateFilter
 from synapse.types import (
     JsonDict,
@@ -55,6 +54,7 @@ from synapse.types import (
 from synapse.util import stringutils
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.response_cache import ResponseCache
+from synapse.util.stringutils import parse_and_validate_server_name
 from synapse.visibility import filter_events_for_client
 
 from ._base import BaseHandler
diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py
index a8376543c9..38461cf79d 100644
--- a/synapse/handlers/saml_handler.py
+++ b/synapse/handlers/saml_handler.py
@@ -78,6 +78,10 @@ class SamlHandler(BaseHandler):
         # user-facing name of this auth provider
         self.idp_name = "SAML"
 
+        # we do not currently support icons for SAML auth, but this is required by
+        # the SsoIdentityProvider protocol type.
+        self.idp_icon = None
+
         # a map from saml session id to Saml2SessionData object
         self._outstanding_requests_dict = {}  # type: Dict[str, Saml2SessionData]
 
diff --git a/synapse/handlers/sso.py b/synapse/handlers/sso.py
index dcc85e9871..d493327a10 100644
--- a/synapse/handlers/sso.py
+++ b/synapse/handlers/sso.py
@@ -75,6 +75,11 @@ class SsoIdentityProvider(Protocol):
     def idp_name(self) -> str:
         """User-facing name for this provider"""
 
+    @property
+    def idp_icon(self) -> Optional[str]:
+        """Optional MXC URI for user-facing icon"""
+        return None
+
     @abc.abstractmethod
     async def handle_redirect_request(
         self,
diff --git a/synapse/http/endpoint.py b/synapse/http/endpoint.py
deleted file mode 100644
index 92a5b606c8..0000000000
--- a/synapse/http/endpoint.py
+++ /dev/null
@@ -1,79 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2014-2016 OpenMarket Ltd
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-import logging
-import re
-
-logger = logging.getLogger(__name__)
-
-
-def parse_server_name(server_name):
-    """Split a server name into host/port parts.
-
-    Args:
-        server_name (str): server name to parse
-
-    Returns:
-        Tuple[str, int|None]: host/port parts.
-
-    Raises:
-        ValueError if the server name could not be parsed.
-    """
-    try:
-        if server_name[-1] == "]":
-            # ipv6 literal, hopefully
-            return server_name, None
-
-        domain_port = server_name.rsplit(":", 1)
-        domain = domain_port[0]
-        port = int(domain_port[1]) if domain_port[1:] else None
-        return domain, port
-    except Exception:
-        raise ValueError("Invalid server name '%s'" % server_name)
-
-
-VALID_HOST_REGEX = re.compile("\\A[0-9a-zA-Z.-]+\\Z")
-
-
-def parse_and_validate_server_name(server_name):
-    """Split a server name into host/port parts and do some basic validation.
-
-    Args:
-        server_name (str): server name to parse
-
-    Returns:
-        Tuple[str, int|None]: host/port parts.
-
-    Raises:
-        ValueError if the server name could not be parsed.
-    """
-    host, port = parse_server_name(server_name)
-
-    # these tests don't need to be bulletproof as we'll find out soon enough
-    # if somebody is giving us invalid data. What we *do* need is to be sure
-    # that nobody is sneaking IP literals in that look like hostnames, etc.
-
-    # look for ipv6 literals
-    if host[0] == "[":
-        if host[-1] != "]":
-            raise ValueError("Mismatched [...] in server name '%s'" % (server_name,))
-        return host, port
-
-    # otherwise it should only be alphanumerics.
-    if not VALID_HOST_REGEX.match(host):
-        raise ValueError(
-            "Server name '%s' contains invalid characters" % (server_name,)
-        )
-
-    return host, port
diff --git a/synapse/res/templates/sso_login_idp_picker.html b/synapse/res/templates/sso_login_idp_picker.html
index f53c9cd679..5b38481012 100644
--- a/synapse/res/templates/sso_login_idp_picker.html
+++ b/synapse/res/templates/sso_login_idp_picker.html
@@ -17,6 +17,9 @@
                     <li>
                         <input type="radio" name="idp" id="prov{{loop.index}}" value="{{p.idp_id}}">
                         <label for="prov{{loop.index}}">{{p.idp_name | e}}</label>
+{% if p.idp_icon %}
+                        <img src="{{p.idp_icon | mxc_to_http(32, 32)}}"/>
+{% endif %}
                     </li>
 {% endfor %}
                 </ul>
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index e6725b03b0..f95627ee61 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -32,7 +32,6 @@ from synapse.api.errors import (
 )
 from synapse.api.filtering import Filter
 from synapse.events.utils import format_event_for_client_v2
-from synapse.http.endpoint import parse_and_validate_server_name
 from synapse.http.servlet import (
     RestServlet,
     assert_params_in_dict,
@@ -47,7 +46,7 @@ from synapse.storage.state import StateFilter
 from synapse.streams.config import PaginationConfig
 from synapse.types import RoomAlias, RoomID, StreamToken, ThirdPartyInstanceID, UserID
 from synapse.util import json_decoder
-from synapse.util.stringutils import random_string
+from synapse.util.stringutils import parse_and_validate_server_name, random_string
 
 if TYPE_CHECKING:
     import synapse.server
diff --git a/synapse/storage/databases/main/room.py b/synapse/storage/databases/main/room.py
index 284f2ce77c..a9fcb5f59c 100644
--- a/synapse/storage/databases/main/room.py
+++ b/synapse/storage/databases/main/room.py
@@ -16,7 +16,6 @@
 
 import collections
 import logging
-import re
 from abc import abstractmethod
 from enum import Enum
 from typing import Any, Dict, List, Optional, Tuple
@@ -30,6 +29,7 @@ from synapse.storage.databases.main.search import SearchStore
 from synapse.types import JsonDict, ThirdPartyInstanceID
 from synapse.util import json_encoder
 from synapse.util.caches.descriptors import cached
+from synapse.util.stringutils import MXC_REGEX
 
 logger = logging.getLogger(__name__)
 
@@ -660,8 +660,6 @@ class RoomWorkerStore(SQLBaseStore):
             The local and remote media as a lists of tuples where the key is
             the hostname and the value is the media ID.
         """
-        mxc_re = re.compile("^mxc://([^/]+)/([^/#?]+)")
-
         sql = """
             SELECT stream_ordering, json FROM events
             JOIN event_json USING (room_id, event_id)
@@ -688,7 +686,7 @@ class RoomWorkerStore(SQLBaseStore):
                 for url in (content_url, thumbnail_url):
                     if not url:
                         continue
-                    matches = mxc_re.match(url)
+                    matches = MXC_REGEX.match(url)
                     if matches:
                         hostname = matches.group(1)
                         media_id = matches.group(2)
diff --git a/synapse/types.py b/synapse/types.py
index 20a43d05bf..eafe729dfe 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -37,7 +37,7 @@ from signedjson.key import decode_verify_key_bytes
 from unpaddedbase64 import decode_base64
 
 from synapse.api.errors import Codes, SynapseError
-from synapse.http.endpoint import parse_and_validate_server_name
+from synapse.util.stringutils import parse_and_validate_server_name
 
 if TYPE_CHECKING:
     from synapse.appservice.api import ApplicationService
diff --git a/synapse/util/stringutils.py b/synapse/util/stringutils.py
index b103c8694c..f8038bf861 100644
--- a/synapse/util/stringutils.py
+++ b/synapse/util/stringutils.py
@@ -18,6 +18,7 @@ import random
 import re
 import string
 from collections.abc import Iterable
+from typing import Optional, Tuple
 
 from synapse.api.errors import Codes, SynapseError
 
@@ -26,6 +27,15 @@ _string_with_symbols = string.digits + string.ascii_letters + ".,;:^&*-_+=#~@"
 # https://matrix.org/docs/spec/client_server/r0.6.0#post-matrix-client-r0-register-email-requesttoken
 client_secret_regex = re.compile(r"^[0-9a-zA-Z\.\=\_\-]+$")
 
+# https://matrix.org/docs/spec/client_server/r0.6.1#matrix-content-mxc-uris,
+# together with https://github.com/matrix-org/matrix-doc/issues/2177 which basically
+# says "there is no grammar for media ids"
+#
+# The server_name part of this is purposely lax: use parse_and_validate_mxc for
+# additional validation.
+#
+MXC_REGEX = re.compile("^mxc://([^/]+)/([^/#?]+)$")
+
 # random_string and random_string_with_symbols are used for a range of things,
 # some cryptographically important, some less so. We use SystemRandom to make sure
 # we get cryptographically-secure randoms.
@@ -59,6 +69,88 @@ def assert_valid_client_secret(client_secret):
         )
 
 
+def parse_server_name(server_name: str) -> Tuple[str, Optional[int]]:
+    """Split a server name into host/port parts.
+
+    Args:
+        server_name: server name to parse
+
+    Returns:
+        host/port parts.
+
+    Raises:
+        ValueError if the server name could not be parsed.
+    """
+    try:
+        if server_name[-1] == "]":
+            # ipv6 literal, hopefully
+            return server_name, None
+
+        domain_port = server_name.rsplit(":", 1)
+        domain = domain_port[0]
+        port = int(domain_port[1]) if domain_port[1:] else None
+        return domain, port
+    except Exception:
+        raise ValueError("Invalid server name '%s'" % server_name)
+
+
+VALID_HOST_REGEX = re.compile("\\A[0-9a-zA-Z.-]+\\Z")
+
+
+def parse_and_validate_server_name(server_name: str) -> Tuple[str, Optional[int]]:
+    """Split a server name into host/port parts and do some basic validation.
+
+    Args:
+        server_name: server name to parse
+
+    Returns:
+        host/port parts.
+
+    Raises:
+        ValueError if the server name could not be parsed.
+    """
+    host, port = parse_server_name(server_name)
+
+    # these tests don't need to be bulletproof as we'll find out soon enough
+    # if somebody is giving us invalid data. What we *do* need is to be sure
+    # that nobody is sneaking IP literals in that look like hostnames, etc.
+
+    # look for ipv6 literals
+    if host[0] == "[":
+        if host[-1] != "]":
+            raise ValueError("Mismatched [...] in server name '%s'" % (server_name,))
+        return host, port
+
+    # otherwise it should only be alphanumerics.
+    if not VALID_HOST_REGEX.match(host):
+        raise ValueError(
+            "Server name '%s' contains invalid characters" % (server_name,)
+        )
+
+    return host, port
+
+
+def parse_and_validate_mxc_uri(mxc: str) -> Tuple[str, Optional[int], str]:
+    """Parse the given string as an MXC URI
+
+    Checks that the "server name" part is a valid server name
+
+    Args:
+        mxc: the (alleged) MXC URI to be checked
+    Returns:
+        hostname, port, media id
+    Raises:
+        ValueError if the URI cannot be parsed
+    """
+    m = MXC_REGEX.match(mxc)
+    if not m:
+        raise ValueError("mxc URI %r did not match expected format" % (mxc,))
+    server_name = m.group(1)
+    media_id = m.group(2)
+    host, port = parse_and_validate_server_name(server_name)
+    return host, port, media_id
+
+
 def shortstr(iterable: Iterable, maxitems: int = 5) -> str:
     """If iterable has maxitems or fewer, return the stringification of a list
     containing those items.
diff --git a/tests/http/test_endpoint.py b/tests/http/test_endpoint.py
index b2e9533b07..d06ea518ce 100644
--- a/tests/http/test_endpoint.py
+++ b/tests/http/test_endpoint.py
@@ -12,7 +12,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from synapse.http.endpoint import parse_and_validate_server_name, parse_server_name
+from synapse.util.stringutils import parse_and_validate_server_name, parse_server_name
 
 from tests import unittest