PNS Saad (S139) is a diesel-electrical Khalid-class submarine of the Pakistan Navy. The Khalid class is an indigenously built sbumarine built by Karachi Shipyard and Engineering Works and Pakistan Naval Engineering Branch, with full assistance provided by French naval engineers. She is based on Agosta 90B design, which is an improved version of the original Agosta class, in service in the Pakistan Navy as the Hashmat class.