Dawn Ostroff, entertainment president of The CW, will step down at the end of the season.

Ostroff, the former head of UPN, has been with The CW since its inception and is the longest-running sitting broadcast president.

According to Deadline Hollywood, Ostroff will remain active with the network as her contract winds down in June. She'll oversee the midseason launch and order pilots for the fall 2011 season.

In other TV news ...

• Damian Lewis has joined the cast of Showtime's 'Homeland.' The 'Life' veteran will play the male lead, Marine Sergeant Scott Brody, who returns home after spending eight years as a prisoner of war in Baghdad. Claire Danes also stars as Carrie Anderson, a CIA agent who suspects Brody may be plotting an attack on America. [Deadline Hollywood]

• Cartoon Network's 'Young Justice' will premiere on Jan. 7. The show about DC Comics sidekicks launched with a movie event in November. Look for new episodes to air Fridays at 7PM. [Kryptonsite]

• Disney was denied its appeal of a $319 million 'Millionaire' verdict. A federal judge ruled that Disney/ABC and Buena Vista cheated producer Celador International out of millions of dollars by cutting sweetheart deals to bring 'Who Wants to be a Millionaire?' to America. [Hollywood Reporter]