Benjamin Bratt is returning to TV with a role on ABC's 'Private Practice.' The 'Law & Order' veteran will be a series regular on the medical drama.

According to the Hollywood Reporter, Bratt will appear in the season 4 finale before joining the cast as a regular in season 5. Details about Bratt's role are being kept under tight wraps.

Bratt is just the latest cast change to the 'Grey's Anatomy' spinoff. Audra McDonald will leave the show after this season and Brian Benben and Caterina Scorsone were upped to series regulars.

In other casting news ...

• Heather Locklear has joined the cast of CBS's pilot 'The Assistants.' Locklear will play one part of a celebrity couple who has a crack team of assistants to look out for their every whim. [Entertainment Weekly]

• Michelle Trachtenberg will star in CBS's untitled comedy pilot about a venture capital firm. The 'Buffy the Vampire Slayer' veteran will play a mail room clerk who gets promoted to junior associate. [EW]

• Dominic Purcell is heading to 'Castle.' The 'Prison Break' veteran will play a Hollywood businessman who may have a connection to a murder. [TVLine]

• '24' star Mary Lynn Rajskub is eying a return to TV in CBS's 'How to Be a Gentleman.' Kevin Dillon will also star in the buddy comedy about a columnist. [EW]

• Will Nicki Minaj join Simon Cowell's 'X Factor'? The R&B singer is reportedly in talks to join the judging panel that already includes L.A. Reid. Rumored judges also include Paula Abdul and Enrique Iglesias. [NY Post]