The samuhakalahom (Thai: สมุหกลาโหม) was one of the two chief ministers in the historical Chatusadom government system of Siam (now Thailand) in use from the Ayutthaya through early Rattanakosin periods. The post was originally charged with military affairs but later oversaw both civil and military affairs in southern cities. Officials who held the post usually received the noble title of Mahasena (Thai: มหาเสนา).