Former "Sopranos" mobster Vincent Pastore is joining the cast of "The Practice" for a few episodes, and possibly the new show that rises from its ashes next fall.

Elsewhere, Jason Isaacs is headed to "The West Wing" for several episodes, and pilots at NBC, UPN and The WB have added to their casts.

Pastore has signed to do a three-episode arc on the ABC series later this season, according to The Hollywood Reporter. He'll play a lawyer who has a run-in with Jimmy Berluti (Michael Badalucco), and his character could show up again in the spin-off -- or "evolution," as ABC calls it -- creator David E. Kelley is planning.

He joins a handful of actors, including current "Practice" star James Spader, William Shatner and Rebecca De Mornay, who are appearing in the show's final episodes and will likely move on to the new series.

Pastore played Salvatore "Big Pussy" Bonpensiero on the first two seasons of "The Sopranos." According to the Reporter, his now-dead character will be seen again later this season.

NBC's "The West Wing," meanwhile, has signed Isaacs ("Peter Pan," "Black Hawk Down") to play a photographer and love interest for the perpetually unlucky Donna Moss (Janel Moloney) in a three-episode arc. The British actor played Lucius Malfoy in "Harry Potter and the Chamber of Secrets."

On the pilot front, The WB has beefed up the casts of several of its pilots. Johann Urb will play a friend and possible rival to Oliver Hudson in the drama "The Mountain," Eric Nenninger ("Malcolm in the Middle") has joined the comedy "Then Came Marriage" (also known as "Marriage 101"), and Ricky Mabe will play one of the kids cared for by a "Commando Nanny," the net's Mark Burnett-produced comedy.

At UPN, Gariyaki Mutambirwa ("Jeepers Creepers II") and Nadege August have joined the cast of the drama "Silver Lake," about a record-store owner (Kerr Smith) who can communicate with the dead. They'll play a close friend and a co-worker of Smith's character.

Finally, twins Brittney and Chelsey Coyle have joined the cast of NBC's limited series "Revelations," which stars Bill Pullman as a man trying to stop the apocalypse.