diff --git a/app/Http/Controllers/Auth/RegisteredUserController.php b/app/Http/Controllers/Auth/RegisteredUserController.php
index f9d31ca..96dbff0 100644
--- a/app/Http/Controllers/Auth/RegisteredUserController.php
+++ b/app/Http/Controllers/Auth/RegisteredUserController.php
@@ -6,6 +6,7 @@ use App\Http\Controllers\Controller;
 use App\Models\User;
 use App\Notifications\NewUserRegistered;
 use App\Rules\NotDisposableEmail;
+use App\Rules\ReservedIdentifier;
 use Illuminate\Auth\Events\Registered;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\Hash;
@@ -27,8 +28,8 @@ class RegisteredUserController extends Controller
         }
 
         $request->validate([
-            'name'        => ['required', 'string', 'max:255'],
-            'email'       => ['required', 'string', 'email', 'max:255', 'unique:users', new NotDisposableEmail],
+            'name'        => ['required', 'string', 'max:255', new ReservedIdentifier('name')],
+            'email'       => ['required', 'string', 'email', 'max:255', 'unique:users', new NotDisposableEmail, new ReservedIdentifier('email')],
             'password'    => ['required', 'confirmed', Password::defaults()],
             'birthday'    => ['required', 'date', 'before:today'],
             'gender'      => ['required', 'in:male,female'],
diff --git a/app/Rules/ReservedIdentifier.php b/app/Rules/ReservedIdentifier.php
new file mode 100644
index 0000000..1cd2918
--- /dev/null
+++ b/app/Rules/ReservedIdentifier.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace App\Rules;
+
+use Closure;
+use Illuminate\Contracts\Validation\ValidationRule;
+
+/**
+ * Blocks impersonation of staff/system accounts.
+ *
+ * Applied to both `name` and the email local-part at registration so a user
+ * cannot sign up as "admin", "superadmin", "takeone", etc. — words that would
+ * let them pass themselves off as the platform or its operators to other
+ * users (comments, DMs, channel pages).
+ */
+class ReservedIdentifier implements ValidationRule
+{
+    private const RESERVED = [
+        'admin', 'administrator', 'superadmin', 'super-admin', 'super_admin',
+        'root', 'sysadmin', 'system', 'owner', 'webmaster', 'postmaster',
+        'moderator', 'mod', 'staff', 'official',
+        'support', 'help', 'helpdesk', 'contact', 'info', 'noreply', 'no-reply',
+        'security', 'abuse', 'billing',
+        'takeone', 'take-one', 'take_one', 'takeonebh', 'takeone-bh',
+        'play', 'playbh', 'playtakeone',
+        'anonymous', 'guest', 'null', 'undefined',
+    ];
+
+    public function __construct(private readonly string $kind = 'name')
+    {
+    }
+
+    public function validate(string $attribute, mixed $value, Closure $fail): void
+    {
+        if (! is_string($value)) {
+            return;
+        }
+
+        $candidate = $this->kind === 'email'
+            ? strtolower(trim(strstr($value, '@', true) ?: $value))
+            : strtolower(trim($value));
+
+        // Collapse separators so "super_admin", "super-admin" and "superadmin" all match.
+        $normalized = preg_replace('/[\s._\-]+/', '', $candidate) ?? $candidate;
+
+        foreach (self::RESERVED as $word) {
+            $target = preg_replace('/[\s._\-]+/', '', $word) ?? $word;
+            if ($normalized === $target) {
+                $fail($this->kind === 'email'
+                    ? 'That email address is reserved. Please use a different one.'
+                    : 'That name is reserved. Please choose a different one.');
+                return;
+            }
+        }
+    }
+}