Casting Notes: Julia Stiles Officially Joins Dexter; Justin Theroux In Wanderlust; Jason O'Mara In Terra Nova

There has been a lot of talk about this over the past couple weeks, but now its official: Julia Stiles is part of the cast of Dexter's fifth season on Showtime. When originally rumored, there was no info on her role. Showtime's official statement says she'll appear in ten episodes of the next season as " a mysterious young woman who forms a unique relationship with Dexter (Michael C. Hall) in the wake of" the end of the fourth season. I edited a season four spoiler out of that line, but if you've been following the show you can mentally insert the relevant info. [Deadline]

After the break, Iron Man 2 writer Justin Theroux gets Wanderlust, and Spielberg's TV series Terra Nova may have a lead actor.

Justin Theroux has an interesting career. When his name comes up I still think of Mulholland Drive before anything else — his turn as the petulant movie director in David Lynch's film defined him for me. But he was also a credited script doctor on Tropic Thunder and got sole credit for writing Iron Man 2. He may end up directing Zoolander 2, if that movie really goes forward.

But he remains an actor (sometimes), and will next appear in Your Highness. And now he's booked the comedy Wanderlust, alongside Paul Rudd and Jennifer Aniston. That's the film David Wain is directing (script by Wain, Rudd and Ken Marino) about a couple in the '70s that escapes the city and ends up living on a commune.[Deadline]

Finally, we've wondered who might lead the cast of Terra Nova, the TV show featuring a time traveling family that was picked up by Fox as a midseason replacement. (Assuming it gets shot in time, that is.) Jason O'Mara (Life on Mars) is now in talks with the producers to star; he'd be the father in the family that travels back to a prehistoric era. The catch is that the role requires moving to Australia for the duration of the shoot. Might be the reason Kyle Chandler passed when offered the role, though at that point we were hearing the series would shoot in Hawaii — much closer, less of a deal-breaker, you'd think. [EW]