Yasiin Bey, previously and more commonly known by his stage name Mos Def, is an American rapper, singer, songwriter, and actor. His hip hop career began in 1994, alongside his siblings in the short-lived rap group Urban Thermo Dynamics, after which they appeared on albums by Da Bush Babees and De La Soul. He formed the duo Black Star, alongside fellow Brooklyn-based rapper Talib Kweli, and in 1998 they released their debut album Mos Def & Talib Kweli Are Black Star, featuring the singles "Definition" and "Respiration". He was featured on the roster of Rawkus Records and in 1999 released his solo debut, Black on Both Sides. His debut was followed by The New Danger, True Magic, and The Ecstatic. About.com listed him 14th on its "50 Greatest Rappers of All Time". His hits include "Oh No", "Ms. Fat Booty", and "Mathematics". He was a child actor in television films, sitcoms, and theater.