diff --git a/backend/src/routes/user/user.service.ts b/backend/src/routes/user/user.service.ts
index 08017f7..77365c0 100644
--- a/backend/src/routes/user/user.service.ts
+++ b/backend/src/routes/user/user.service.ts
@@ -155,6 +155,16 @@ export class UserService {
     async updateUser(id: string, dto: UpdateUserDto, currentUser: Users): Promise<Users> {
         const user = await this.findOne(id);
 
+        // Le super administrateur conserve une identité figée.
+        if (
+            user.role === RoleType.SUPER_ADMIN &&
+            (dto.nom !== undefined || dto.prenom !== undefined)
+        ) {
+            throw new ForbiddenException(
+                'Le nom et le prénom du super administrateur ne peuvent pas être modifiés',
+            );
+        }
+
         // Interdire changement de rôle si pas super admin
         if (dto.role && currentUser.role !== RoleType.SUPER_ADMIN) {
             throw new ForbiddenException('Accès réservé aux super admins');
@@ -251,6 +261,12 @@ export class UserService {
         if (currentUser.role !== RoleType.SUPER_ADMIN) {
             throw new ForbiddenException('Accès réservé aux super admins');
         }
+        const user = await this.findOne(id);
+        if (user.role === RoleType.SUPER_ADMIN) {
+            throw new ForbiddenException(
+                'Le super administrateur ne peut pas être supprimé',
+            );
+        }
         const result = await this.usersRepository.delete(id);
         if (result.affected === 0) {
             throw new NotFoundException('Utilisateur introuvable');
diff --git a/frontend/lib/screens/administrateurs/creation/gestionnaires_create.dart b/frontend/lib/screens/administrateurs/creation/gestionnaires_create.dart
index 9417eae..9a79fbb 100644
--- a/frontend/lib/screens/administrateurs/creation/gestionnaires_create.dart
+++ b/frontend/lib/screens/administrateurs/creation/gestionnaires_create.dart
@@ -39,6 +39,10 @@ class _AdminUserFormDialogState extends State<AdminUserFormDialog> {
   List<RelaisModel> _relais = [];
   String? _selectedRelaisId;
   bool get _isEditMode => widget.initialUser != null;
+  bool get _isSuperAdminTarget =>
+      widget.initialUser?.role.toLowerCase() == 'super_admin';
+  bool get _isLockedAdminIdentity =>
+      _isEditMode && widget.adminMode && _isSuperAdminTarget;
 
   @override
   void initState() {
@@ -212,10 +216,12 @@ class _AdminUserFormDialogState extends State<AdminUserFormDialog> {
 
       if (_isEditMode) {
         if (widget.adminMode) {
+          final lockedNom = _toTitleCase(widget.initialUser!.nom ?? '');
+          final lockedPrenom = _toTitleCase(widget.initialUser!.prenom ?? '');
           await UserService.updateAdministrateur(
             adminId: widget.initialUser!.id,
-            nom: normalizedNom,
-            prenom: normalizedPrenom,
+            nom: _isLockedAdminIdentity ? lockedNom : normalizedNom,
+            prenom: _isLockedAdminIdentity ? lockedPrenom : normalizedPrenom,
             email: _emailController.text.trim(),
             telephone: normalizedPhone.isEmpty
                 ? _normalizePhone(widget.initialUser!.telephone ?? '')
@@ -308,6 +314,7 @@ class _AdminUserFormDialogState extends State<AdminUserFormDialog> {
 
   Future<void> _delete() async {
     if (widget.readOnly) return;
+    if (_isSuperAdminTarget) return;
     if (!_isEditMode || _isSubmitting) return;
 
     final confirmed = await showDialog<bool>(
@@ -430,11 +437,12 @@ class _AdminUserFormDialogState extends State<AdminUserFormDialog> {
             child: const Text('Fermer'),
           ),
         ] else if (_isEditMode) ...[
-          OutlinedButton(
-            onPressed: _isSubmitting ? null : _delete,
-            style: OutlinedButton.styleFrom(foregroundColor: Colors.red.shade700),
-            child: const Text('Supprimer'),
-          ),
+          if (!_isSuperAdminTarget)
+            OutlinedButton(
+              onPressed: _isSubmitting ? null : _delete,
+              style: OutlinedButton.styleFrom(foregroundColor: Colors.red.shade700),
+              child: const Text('Supprimer'),
+            ),
           FilledButton.icon(
             onPressed: _isSubmitting ? null : _submit,
             icon: _isSubmitting
@@ -471,26 +479,30 @@ class _AdminUserFormDialogState extends State<AdminUserFormDialog> {
   Widget _buildNomField() {
     return TextFormField(
       controller: _nomController,
-      readOnly: widget.readOnly,
+      readOnly: widget.readOnly || _isLockedAdminIdentity,
       textCapitalization: TextCapitalization.words,
       decoration: const InputDecoration(
         labelText: 'Nom',
         border: OutlineInputBorder(),
       ),
-      validator: widget.readOnly ? null : (v) => _required(v, 'Nom'),
+      validator: (widget.readOnly || _isLockedAdminIdentity)
+          ? null
+          : (v) => _required(v, 'Nom'),
     );
   }
 
   Widget _buildPrenomField() {
     return TextFormField(
       controller: _prenomController,
-      readOnly: widget.readOnly,
+      readOnly: widget.readOnly || _isLockedAdminIdentity,
       textCapitalization: TextCapitalization.words,
       decoration: const InputDecoration(
         labelText: 'Prénom',
         border: OutlineInputBorder(),
       ),
-      validator: widget.readOnly ? null : (v) => _required(v, 'Prénom'),
+      validator: (widget.readOnly || _isLockedAdminIdentity)
+          ? null
+          : (v) => _required(v, 'Prénom'),
     );
   }