diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index 590887b3cad..9502a9c404d 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -18,6 +18,7 @@ apps/cli/src/auth @bitwarden/team-auth-dev
 apps/desktop/src/auth @bitwarden/team-auth-dev
 apps/web/src/app/auth @bitwarden/team-auth-dev
 libs/auth @bitwarden/team-auth-dev
+libs/user-core @bitwarden/team-auth-dev
 # web connectors used for auth
 apps/web/src/connectors @bitwarden/team-auth-dev
 bitwarden_license/bit-web/src/app/auth @bitwarden/team-auth-dev
diff --git a/libs/common/src/types/guid.ts b/libs/common/src/types/guid.ts
index bf891b55691..5edd34e4fc5 100644
--- a/libs/common/src/types/guid.ts
+++ b/libs/common/src/types/guid.ts
@@ -2,7 +2,9 @@ import { Opaque } from "type-fest";
 
 export type Guid = Opaque<string, "Guid">;
 
-export type UserId = Opaque<string, "UserId">;
+// Convenience re-export of UserId from it's original location, any library that
+// wants to be lower level than common should instead import it from user-core.
+export { UserId } from "@bitwarden/user-core";
 export type OrganizationId = Opaque<string, "OrganizationId">;
 export type CollectionId = Opaque<string, "CollectionId">;
 export type ProviderId = Opaque<string, "ProviderId">;
diff --git a/libs/user-core/README.md b/libs/user-core/README.md
new file mode 100644
index 00000000000..57975746606
--- /dev/null
+++ b/libs/user-core/README.md
@@ -0,0 +1,6 @@
+# user-core
+
+Owned by: auth
+
+The very basic concept that constitutes a user, this needs to be very low level to facilitate
+Platform keeping their own code low level.
diff --git a/libs/user-core/eslint.config.mjs b/libs/user-core/eslint.config.mjs
new file mode 100644
index 00000000000..9c37d10e3ff
--- /dev/null
+++ b/libs/user-core/eslint.config.mjs
@@ -0,0 +1,3 @@
+import baseConfig from "../../eslint.config.mjs";
+
+export default [...baseConfig];
diff --git a/libs/user-core/jest.config.js b/libs/user-core/jest.config.js
new file mode 100644
index 00000000000..e38a12f3eb5
--- /dev/null
+++ b/libs/user-core/jest.config.js
@@ -0,0 +1,10 @@
+module.exports = {
+  displayName: "user-core",
+  preset: "../../jest.preset.js",
+  testEnvironment: "node",
+  transform: {
+    "^.+\\.[tj]s$": ["ts-jest", { tsconfig: "<rootDir>/tsconfig.spec.json" }],
+  },
+  moduleFileExtensions: ["ts", "js", "html"],
+  coverageDirectory: "../../coverage/libs/user-core",
+};
diff --git a/libs/user-core/package.json b/libs/user-core/package.json
new file mode 100644
index 00000000000..2251d2ceace
--- /dev/null
+++ b/libs/user-core/package.json
@@ -0,0 +1,10 @@
+{
+  "name": "@bitwarden/user-core",
+  "version": "0.0.0",
+  "description": "The very basic concept that constitutes a user, this needs to be very low level to facilitate Platform keeping their own code low level.",
+  "type": "commonjs",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "license": "GPL-3.0",
+  "author": "auth"
+}
diff --git a/libs/user-core/project.json b/libs/user-core/project.json
new file mode 100644
index 00000000000..60d5873208d
--- /dev/null
+++ b/libs/user-core/project.json
@@ -0,0 +1,27 @@
+{
+  "name": "user-core",
+  "$schema": "../../node_modules/nx/schemas/project-schema.json",
+  "sourceRoot": "libs/user-core/src",
+  "projectType": "library",
+  "tags": [],
+  "targets": {
+    "build": {
+      "executor": "@nx/js:tsc",
+      "outputs": ["{options.outputPath}"],
+      "options": {
+        "outputPath": "dist/libs/user-core",
+        "main": "libs/user-core/src/index.ts",
+        "tsConfig": "libs/user-core/tsconfig.lib.json",
+        "assets": ["libs/user-core/*.md"]
+      }
+    },
+    "test": {
+      "executor": "@nx/jest:jest",
+      "outputs": ["{workspaceRoot}/coverage/{projectRoot}"],
+      "options": {
+        "jestConfig": "libs/user-core/jest.config.js",
+        "passWithNoTests": true
+      }
+    }
+  }
+}
diff --git a/libs/user-core/src/index.ts b/libs/user-core/src/index.ts
new file mode 100644
index 00000000000..42e663c851a
--- /dev/null
+++ b/libs/user-core/src/index.ts
@@ -0,0 +1,9 @@
+import { Opaque } from "type-fest";
+
+/**
+ * The main identifier for a user. It is a string that should be in valid guid format.
+ *
+ * You should avoid `as UserId`-ing strings as much as possible and instead retrieve the {@see UserId} from
+ * a valid source instead.
+ */
+export type UserId = Opaque<string, "UserId">;
diff --git a/libs/user-core/tsconfig.json b/libs/user-core/tsconfig.json
new file mode 100644
index 00000000000..62ebbd94647
--- /dev/null
+++ b/libs/user-core/tsconfig.json
@@ -0,0 +1,13 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "files": [],
+  "include": [],
+  "references": [
+    {
+      "path": "./tsconfig.lib.json"
+    },
+    {
+      "path": "./tsconfig.spec.json"
+    }
+  ]
+}
diff --git a/libs/user-core/tsconfig.lib.json b/libs/user-core/tsconfig.lib.json
new file mode 100644
index 00000000000..9cbf6736007
--- /dev/null
+++ b/libs/user-core/tsconfig.lib.json
@@ -0,0 +1,10 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "../../dist/out-tsc",
+    "declaration": true,
+    "types": ["node"]
+  },
+  "include": ["src/**/*.ts"],
+  "exclude": ["jest.config.js", "src/**/*.spec.ts"]
+}
diff --git a/libs/user-core/tsconfig.spec.json b/libs/user-core/tsconfig.spec.json
new file mode 100644
index 00000000000..1275f148a18
--- /dev/null
+++ b/libs/user-core/tsconfig.spec.json
@@ -0,0 +1,10 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "../../dist/out-tsc",
+    "module": "commonjs",
+    "moduleResolution": "node10",
+    "types": ["jest", "node"]
+  },
+  "include": ["jest.config.ts", "src/**/*.test.ts", "src/**/*.spec.ts", "src/**/*.d.ts"]
+}
diff --git a/package-lock.json b/package-lock.json
index e9701cbd7ee..d7c23e0997b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -427,6 +427,10 @@
       "version": "0.0.0",
       "license": "GPL-3.0"
     },
+    "libs/user-core": {
+      "version": "0.0.0",
+      "license": "GPL-3.0"
+    },
     "libs/vault": {
       "name": "@bitwarden/vault",
       "version": "0.0.0",
@@ -4640,6 +4644,10 @@
       "resolved": "libs/ui/common",
       "link": true
     },
+    "node_modules/@bitwarden/user-core": {
+      "resolved": "libs/user-core",
+      "link": true
+    },
     "node_modules/@bitwarden/vault": {
       "resolved": "libs/vault",
       "link": true
diff --git a/tsconfig.base.json b/tsconfig.base.json
index c820306fd15..c462ab97d37 100644
--- a/tsconfig.base.json
+++ b/tsconfig.base.json
@@ -47,6 +47,7 @@
       "@bitwarden/storage-test-utils": ["libs/storage-test-utils/src/index.ts"],
       "@bitwarden/ui-common": ["./libs/ui/common/src"],
       "@bitwarden/ui-common/setup-jest": ["./libs/ui/common/src/setup-jest"],
+      "@bitwarden/user-core": ["libs/user-core/src/index.ts"],
       "@bitwarden/vault": ["./libs/vault/src"],
       "@bitwarden/vault-export-core": ["./libs/tools/export/vault-export/vault-export-core/src"],
       "@bitwarden/vault-export-ui": ["./libs/tools/export/vault-export/vault-export-ui/src"],