The Big Bang Theory June Squibb ("Nebraska") guest stars as Sheldon's (Jim Parsons) often-mentioned but previously unseen "Meemaw," whose visit thrills her grandson — until she meets Amy (Mayim Bialik) in this new episode of the smart comedy. 8 p.m. CBS
You, Me and the Apocalypse Global riots break out as the comet draws nearer, so all eyes are on Scotty McNeil (Kyle Soller) and his plan to save the world in this new episode. 8 p.m. NBC
DC's Legends of Tomorrow In this new episode Rip (Arthur Darville) hatches a scheme to weaken Vandal Savage (Casper Crump) by going after...