Ugly Betty (7 p.m., Ch. 4): Wilhelmina returns to Mode.

Smallville (7 p.m., Ch. 30): Clark and Lex face off. (Season finale)

My Name Is Earl (7 p.m., Ch. 5): Billie gives Earl an ultimatum. (One-hour season finale)

CSI (8 p.m., Ch. 2): Did Warrick kill a gangster? (Season finale)

Grey's Anatomy (8 p.m., Ch. 4): Alex learns the truth about Rebecca.

The Office (8 p.m., Ch. 5): Michael throws Toby a big farewell party. (One-hour season finale)

Supernatural (8 p.m., Ch. 30): Sam tries to save Dean from hell. (Season finale)

Without a Trace (9:01 p.m., Ch. 2): Five people are abducted. (Season finale)

Lost (9:02 p.m., Ch. 4): The battle begins.

ER (9:01 p.m., Ch. 5): Steve Buscemi guest stars as a drunken patient. (Season finale)