“CSI” (9 p.m., CBS): Tonight on “CSI: Crime Scene Investigation,” we bid a

“CSI” (9 p.m., CBS): Tonight on “CSI: Crime Scene Investigation,” we bid a sad farewell to Gil Grissom (William Petersen), with whom we’ve shared so much, including gruesome decapitations, transgender serial killers and decomposing pigs.

“30 Rock” (9:30 p.m., NBC): A flu around the office spurs Liz to make sure everyone gets a shot -- or else.

“The Beast” (10 p.m., A&E): “The Beast” is a new drama series starring Patrick Swayze as a maverick FBI veteran who gets teamed with a rookie (Travis Fimmel). But with that rather conventional premise, can it ever be a beast in the ratings?

“Treasure Quest” (10 p.m., Discovery): It’s a treasure hunt that really goes deep. Discovery Channel’s “Treasure Quest” takes viewers to the ocean floor in search of artifacts from a few of the 3 million shipwrecks beckoning from far below.