“Big Bang Theory” (8 p.m., CBS): The reigning champion of sitcomdom restarts its 12th

“Big Bang Theory” (8 p.m., CBS): The reigning champion of sitcomdom restarts its 12th and final season after the winter break. Penny and Leonard organize a paintball game that results in mayhem when Sheldon is jealous of Amy.

“Gotham” (8 p.m., Fox): Jim Gordon and Bruce Wayne face the chaos Gotham City has become as this Batman origins drama begins its fifth season.

“Titan Games” (8 p.m., NBC): It’s the two-hour season premiere of this athletic competition show created and hosted by Dwayne Johnson.

“The Last Days of JFK Jr.” (9 p.m., ABC): A two-hour documentary about the life of John F. Kennedy Jr., who died, along with his wife and her sister, in a plane crash 20 years ago.

TV listings, B7