Rapper-turned-actor Mos Def is the latest addition to 'Dexter' as the Showtime series adds to the cast for its sixth season.

Mos Def's multi-episode arc will see him play a born again ex-con who "seems to continually find himself surrounded by violence," according to The Hollywood Reporter. As expected, Dexter "will reveal the truth of who he really is."

The actor joins Colin Hanks as one of Dexter's season six nemeses.

In other TV news ...

• Will Smith and Jada Pinkett Smith will appear on the 'Oprah' finale. The husband and wife team will chat with Winfrey as she says goodbye after 25 years. The final episode is scheduled to air on May 25. [TV Guide]

• Seth Gabel has been promoted to series regular on 'Fringe.' The 'Dirty Sexy Money' actor has recurred on the Fox sci-fi drama for the past two seasons as Lincoln Lee. [TV Line]

• 'Falling Skies' hasn't even premiered yet and already TNT is considering a season 2. The network is reportedly looking to hire a showrunner for the potential second season. [Deadline]

• 'The Voice' ratings fell in the singing competition's third week. The series still beat 'Glee,' however, in both total viewers and the 18-49 demographic. [EW]

• WE tv renewed 'Braxton Family Values' for a second season. The reality show follows singer Toni Braxton and her sisters. [Deadline]