Mark Alexander Knox, better known as Flex Alexander or Flex, is an actor, comedian and dancer. Alexander's first television role was on the short-lived 1993 ABC sitcom Where I Live, starring Doug E. Doug. From 2000 to 2001, Alexander appeared as Maya Wilkes' husband Darnell during the first season of the UPN sitcom Girlfriends. He left Girlfriends to star as single father Mark "Flex" Washington on the UPN sitcom One on One, a series he created and produced. Other notable credits include Sister, Sister and The Cosby Mysteries, and the film She's All That.