TV Today

The Ellen DeGeneres Show

(3-4 p.m., NBC10) - Actor Benjamin Bratt (

The Cleaner

); Nelly, Akon and Ashanti perform; 10-year-old motivational speaker Dalton Sherman.

Smallville

(8-9 p.m., CW57) - We finally find out what happened to Clark (Tom Welling) after the collapse of the fortress in the season premiere. The Justice League heads to the Arctic in search of Clark and immediately has a confrontation with the new chief executive of Luthorcorp, Tess Mercer (Cassidy Freeman).

Grey's Anatomy

(9-11 p.m., 6ABC) - Meredith and Derek need some concrete results. While they take their last shots at success in their clinical trials, the other surgeons try to free a boy from a block of concrete before it hardens.

What Happened to Natalie Holloway?

(11 p.m.-midnight, A&E) - Bill Kurtis revisits the disappearance of 18-year-old Natalee Holloway, who was last seen publicly leaving a bar in Aruba on May 30, 2005. Kurtis interviews Natalee's mother, Beth; an Aruban prosecutor looking for the truth; an underwater-crime-scene expert searching for Natalee's remains; and an Aruban police detective is still working on the case.

Late Show With David Letterman

(11:35 p.m.-12:35 a.m., CBS3) - Actor Seth Rogen; the Fleet Foxes perform.

The Tonight Show With Jay Leno

(11:35 p.m.-12:35 a.m., NBC10) - Actor Dane Cook; actress Kristen Bell; Hawthorne Heights performs.

Jimmy Kimmel Live

(12:05-1:05 a.m., 6ABC) - Actor Ricky Gervais; actress Carla Gugino; Good Charlotte performs.

The Late Late Show With Craig Ferguson

(12:35-1:35 a.m., CBS3) - Actor Jason Segel; comic Steve Hofstetter.

Late Night With Conan O'Brien

(12:35-1:35 a.m., NBC10) - Musician Willie Nelson; Southside Johnny performs with La Bamba's Big Band.