Prior to his role in "The Fresh Prince of Bel-Air," Marcell was already an accomplished theatre actor, with acting credits in Shakespearean plays "Othello" and "A Midsummer Night's Dream." Following the end of the show, Marcell continued to act in film and TV but focussed mainly on theatre.
He is a member of the Royal Shakespeare Company and a part of the board at Shakespeare's Globe Theatre, where he continues to perform. At one point, he tried to lure costar Smith into the world of Shakespeare, telling The Guardian, "I did want him to play Mark Antony but he was busy with Independence Day."
The actor is married to Joyce T. Walsh and has two children.