ABC has added to the casts of three pilots, with "Firefly's" Morena Baccarin among the signees, and is bringing a familiar face back to one of its existing shows.

Baccarin is joining writer David Hemingson's legal drama, where she'll star opposite Matt Long as new associates at a Los Angeles law firm. Elsewhere, Ruben Santiago-Hudson ("Lackawanna Blues") has signed on to the drama "Castle," and Steve Howey ("Reba") and Lee Thompson Young ("Smallville," "Akeelah and the Bee") have landed parts in the comedy "Five Year Plan," according to The Hollywood Reporter.

Also at ABC, David Sutcliffe will return to "Private Practice" next season to continue his arc as a love interest for Addison (Kate Walsh).

The Hemingson drama centers on Long's character, a recent law-school graduate from a working-class background who joins a boutique law practice. Baccarin will play another new associate, a privileged young woman from Beverly Hills.

"Castle" stars Baccarin's former castmate Nathan Fillion as a mystery novelist who consults with police on murder cases. Santiago-Hudson, whose credits also include "American Gangster" and several "Law & Order" appearances, will play the police chief.

As the title implies, "Five Year Plan" follows a group of friends trying to figure out their futures. Howey will play Mickey, a newly engaged law-school graduate, and Young will play the roommate of Mickey's brother.

Finally, Sutcliffe will reprise his role as cop Kevin Nelson in "Private Practice" next season. The former "Gilmore Girls" actor will appear in as many as 11 episodes of the second-year show.