Osman Mahamuud (, ), also known as `Uthman III ibn Mahmud, was a Somali ruler. He led the Majeerteen Sultanate during its Golden Age in the mid-19th to early 20th centuries. Along with Sultan Yusuf Ali Kenadid of the Sultanate of Hobyo and Sultan Mohamoud Ali Shire of the Warsangali Sultanate, Boqor Osman was one of the three prominent rulers of present-day Somalia at the turn of the 20th century.