diff --git a/src/safeds_stubgen/stubs_generator/_generate_stubs.py b/src/safeds_stubgen/stubs_generator/_generate_stubs.py
index 42e83db8..9ee6ba20 100644
--- a/src/safeds_stubgen/stubs_generator/_generate_stubs.py
+++ b/src/safeds_stubgen/stubs_generator/_generate_stubs.py
@@ -415,17 +415,26 @@ def _create_type_string(self, type_data: dict | None) -> str:
                 return f"{name}<{', '.join(types)}>"
             return f"{name}<Any>"
         elif kind == "UnionType":
-            types = [
+            # Union items have to be unique
+            types = list({
                 self._create_type_string(type_)
                 for type_ in type_data["types"]
-            ]
+            })
 
             if types:
                 if len(types) == 2 and none_type_name in types:
-                    if types[0] == none_type_name:
+                    # if None is one of the two possible types, we can remove the None and just return the other
+                    # type with a question mark
+                    if types[0] == types[1] == none_type_name:
+                        return none_type_name
+                    elif types[0] == none_type_name:
                         return f"{types[1]}?"
-                    else:
-                        return f"{types[0]}?"
+                    return f"{types[0]}?"
+
+                # If the union contains only one type, return the type instead of creating an union
+                elif len(types) == 1:
+                    return types[0]
+
                 return f"union<{', '.join(types)}>"
             return ""
         elif kind == "TupleType":
diff --git a/tests/data/test_stub_generation/function_module.py b/tests/data/test_stub_generation/function_module.py
index 09fd0e85..e04e48cd 100644
--- a/tests/data/test_stub_generation/function_module.py
+++ b/tests/data/test_stub_generation/function_module.py
@@ -37,8 +37,13 @@ def illegal_params(
 
 
 def special_params(
-    none_bool_union: None | bool,
     none_union: None | None,
+    none_bool_union: None | bool,
+    bool_none_union: bool | None,
+    none_bool_none_union: None | bool | None,
+    none_bool_int_union: None | bool | int,
+    none_none_bool_none_union: None | None | bool | None,
+    none_list_union_none_none: None | list[None | None] | None,
     none: None,
 ): ...
 
diff --git a/tests/safeds_stubgen/stubs_generator/test_generate_stubs.py b/tests/safeds_stubgen/stubs_generator/test_generate_stubs.py
index fa23d49d..7275b419 100644
--- a/tests/safeds_stubgen/stubs_generator/test_generate_stubs.py
+++ b/tests/safeds_stubgen/stubs_generator/test_generate_stubs.py
@@ -25,6 +25,7 @@
 stubs_generator.generate_stubs()
 
 
+# Todo Frage: Automatische Einrückung bei .ambr Dateien -> Snapshot Test schlagen deswegen fehl
 # Utilites
 def _assert_file_creation_recursive(python_path: Path, stub_path: Path) -> None:
     assert python_path.is_dir()