There are nine -- count 'em, nine -- season finales tonight, so Thursdays are about to free up for a lot of people.
Among the most notable is "Fringe," (Fox, 9 p.m.), which caps off an excellent sophomore season with Part 2 of a two-parter, featuring guest star Leonard Nimoy in what could be his final performance, since he said he's retiring. It follows the season finale of "Bones," in which Brennan considers leaving the Jeffersonian.
CBS features two serial killers as the teams on "CSI" and "The Mentalist" face off with Dr. Jekyll and Red John, respectively, from 9-11 p.m.
"Grey's Anatomy" (ABC, 9 p.m.) is two hours tonight as a gunman runs wild in the hospital. It follows a new "FlashForward," which won't wrap up until next week.
NBC's sitcoms wrap up tonight with guest stars galore, including Rob Lowe on "Parks & Recreation" at 8:30 p.m., Kathy Bates on "The Office" at 9 p.m. and "30 Rock" featuring Matt Damon, Elizabeth Banks, Julianne Moore and Will Forte, among others. They are followed by the season finale (finally, after they announced it three or four times) of "The Marriage Ref," with guest judges Jim Breuer, Demi Moore and Kelly Ripa.