diff --git a/Neos.Flow/Classes/Reflection/ReflectionService.php b/Neos.Flow/Classes/Reflection/ReflectionService.php
index e7f786c605..26af03a16e 100644
--- a/Neos.Flow/Classes/Reflection/ReflectionService.php
+++ b/Neos.Flow/Classes/Reflection/ReflectionService.php
@@ -1321,10 +1321,8 @@ protected function reflectClassMethod(string $className, MethodReflection $metho
         }
 
         $returnType = $method->getDeclaredReturnType();
-        $applyLeadingSlashIfNeeded = static function (string $type): string {
-            if (!in_array($type, ['self', 'parent', 'static', 'null', 'callable', 'void', 'never', 'iterable', 'object', 'resource', 'mixed'])
-                && !TypeHandling::isSimpleType($type)
-            ) {
+        $applyLeadingSlashIfNeeded = function (string $type): string {
+            if (!str_starts_with($type, '\\') && TypeHandling::isUserDefinedType($type)) {
                 return '\\' . $type;
             }
             return $type;
@@ -1415,8 +1413,8 @@ protected function expandType(ClassReflection $class, string $type): string
             return 'array<' . $this->expandType($class, $elementType) . '>' . ($isNullable ? '|null' : '');
         }
 
-        // skip simple types and types with fully qualified namespaces
-        if ($type === 'mixed' || $type[0] === '\\' || TypeHandling::isSimpleType($type)) {
+        // skip non user-defined types and types with fully qualified namespaces
+        if ($typeWithoutNull[0] === '\\' || !TypeHandling::isUserDefinedType($typeWithoutNull)) {
             return TypeHandling::normalizeType($typeWithoutNull) . ($isNullable ? '|null' : '');
         }
 
@@ -1777,7 +1775,7 @@ protected function convertParameterReflectionToArray(ParameterReflection $parame
         }
 
         $parameterType = $this->renderParameterType($parameter->getType());
-        if ($parameterType !== null && !TypeHandling::isSimpleType($parameterType)) {
+        if ($parameterType !== null && TypeHandling::isUserDefinedType($parameterType)) {
             // We use parameter type here to make class_alias usage work and return the hinted class name instead of the alias
             $parameterInformation[self::DATA_PARAMETER_CLASS] = $parameterType;
         } elseif ($parameterType === 'array') {
diff --git a/Neos.Utility.ObjectHandling/Classes/TypeHandling.php b/Neos.Utility.ObjectHandling/Classes/TypeHandling.php
index a134b02504..66138a477c 100644
--- a/Neos.Utility.ObjectHandling/Classes/TypeHandling.php
+++ b/Neos.Utility.ObjectHandling/Classes/TypeHandling.php
@@ -28,7 +28,22 @@ abstract class TypeHandling
     /**
      * A type pattern to detect literal types.
      */
-    const LITERAL_TYPE_PATTERN = '/^(?:integer|int|float|double|boolean|bool|string)$/';
+    const LITERAL_TYPE_PATTERN = '/^(?:integer|int|float|double|boolean|bool|string|true|false|null)$/';
+
+    /**
+     * A type pattern to detect scalar types.
+     */
+    const SCALAR_TYPE_PATTERN = '/^(?:int|float|bool|string)$/';
+
+    /**
+     * @var array<string>
+     */
+    protected static $builtInTypes = ['null', 'array', 'object', 'resource', 'never', 'void', 'self', 'parent', 'static'];
+
+    /**
+     * @var array<string>
+     */
+    protected static $builtInTypeAliases = ['mixed', 'iterable'];
 
     /**
      * @var array<int,string|class-string<\Traversable<mixed>>>
@@ -96,21 +111,100 @@ public static function normalizeType(string $type): string
      *
      * @param string $type
      * @return boolean
+     * @deprecated use isLiteralType()
      */
     public static function isLiteral(string $type): bool
+    {
+        return self::isLiteralType($type);
+    }
+
+    /**
+     * Returns true if the $type is a scalar type.
+     *
+     * @param string $type
+     * @return bool
+     */
+    public static function isScalarType(string $type): bool
+    {
+        return preg_match(self::SCALAR_TYPE_PATTERN, $type) === 1;
+    }
+
+    /**
+     * Returns true if the $type is a built-in type.
+     *
+     * @param string $type
+     * @return bool
+     */
+    public static function isBuiltInType(string $type): bool
+    {
+        if (self::isScalarType($type)) {
+            return true;
+        }
+
+        return in_array($type, self::$builtInTypes, true);
+    }
+
+    /**
+     * Returns true if the $type is a literal type.
+     *
+     * @param string $type
+     * @return bool
+     */
+    public static function isLiteralType(string $type): bool
     {
         return preg_match(self::LITERAL_TYPE_PATTERN, $type) === 1;
     }
 
+    /**
+     * Returns true if the $type is callable.
+     *
+     * @param string $type
+     * @return bool
+     */
+    public static function isCallableType(string $type): bool
+    {
+        return $type === 'callable';
+    }
+
+    /**
+     * Returns true if the $type is a built-in type alias.
+     *
+     * @param string $type
+     * @return bool
+     */
+    public static function isBuiltInTypeAlias(string $type): bool
+    {
+        return in_array($type, self::$builtInTypeAliases, true);
+    }
+
+    /**
+     * Returns true if the $type is user-defined.
+     *
+     * @param string $type
+     * @return bool
+     */
+    public static function isUserDefinedType(string $type): bool
+    {
+        return !self::isBuiltInType($type)
+            && !self::isLiteralType($type)
+            && !self::isCallableType($type)
+            && !self::isBuiltInTypeAlias($type);
+    }
+
     /**
      * Returns true if the $type is a simple type.
      *
      * @param string $type
      * @return boolean
+     * @deprecated use isBuiltInType(), isLiteralType(), isCallableType() or isBuiltInTypeAlias()
      */
     public static function isSimpleType(string $type): bool
     {
-        return in_array(self::normalizeType($type), ['array', 'string', 'float', 'integer', 'boolean', 'null', 'false', 'true'], true);
+        $normalizedType = self::normalizeType($type);
+
+        return $normalizedType === 'array'
+            || self::isLiteralType($type)
+            || in_array($normalizedType, ['null', 'false', 'true'], true);
     }
 
     /**