Robert Knepper, Madeline Zima

It's a beast ... and a beauty.

Robert Knepper, who repulsed yet riveted Prison Break fans as the vile Theodore "T-Bag" Bagwell, is joining NBC's Heroes as this season's big baddie, says the Hollywood Reporter.

Also, a show rep confirms that Californication's Madeline Zima is coming on board as Claire's new gal pal.

In the Season 4 volume "Redemption," Knepper will play Samuel, the charismatic yet wicked ringmaster of a literal circus. In casting breakdowns leaked last month, the show expressed its want for an Eddie Izzard type to fill the role. Dare I say, they did themselves one better.

Zima, meanwhile, has been cast in the recurring role of Gretchen, an edgy co-ed Claire will cross paths with at college.

Yes, Prison Break fans — Heroes has added a T-Bag and a Gretchen. (It had to be noted.)

Heroes will air an hour earlier this fall — Mondays at 8 pm/ET — and likely run a continuous season à la Lost. NBC has ordered "around 19 episodes" of the sci-fi series, network boss Ben Silverman told TVGuide.com at the May upfronts.

Knepper can next be seen in Prison Break: The Final Break, a made-for-DVD follow-up movie hitting stores July 21.

(Additional reporting by Tim Molloy)

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