Season 6 of 'Dexter' is dripping with fresh blood. And by that we mean there are a lot of new additions to the cast. Showtime released a promo that introduces us to all of the new characters.

Colin Hanks and Edward James Olmos join the cast as this season's villains. Olmos plays a twisted religion professor, Professor Gellar, and Hanks plays his student, Travis. Together, they conspire to carry out what they consider to be divinely-justified murders.

Rapper and actor Mos Def is also joining the cast, playing a character named Brother Sam. Dexter initially starts tracking him as a potential victim, but soon discovers he's rehabilitated himself with religion.

Check out more new character descriptions, and the 'Dexter' promo, after the jump.

Aimee Garcia, formerly of 'Off the Map,' joins the cast as Jamie Batista. She's Sgt. Batista's little sister, Harrison's new nanny, and hangs out in Dexter's apartment wearing a bikini top. I wonder where this is going.

Finally, Billy Brown joins the cast as Mike Anderson, a new addition to the Miami Metro homicide unit. He's from Chicago, and is an all-business straight-shooter who seems perturbed by the shenanigans that go on in his new office. In the promo, he immediately butts heads with Deb.



Season 6 of 'Dexter' premieres Sun., Oct. 9 at 9 PM on Showtime.