Three men are found dead in the new episode Black Widow. When it's noted that they all share similar builds and taste in watches, law enforcement officials believe that they were all murdered by the same person: a black widow. NBC, 9 p.m.
Sex in the Wild
Joy and Mark learn about the reproductive practices of marine mammals in this new episode. They examine how these animals can mate, give birth and raise their young under water, despite being creatures that breathe air. PBS, 9 p.m.
Who Do You Think You Are?
Get a look at actress Rachel McAdams' family tree in this new episode. Each episode takes a close look into a celebrity's ancestry, often uncovering fascinating historical events and activities that occurred in the family's past. TLC, 8 p.m.
George Stroumboulopoulos: William Shatner
David Letterman: Martha Stewart, Bill Murray
Jimmy Fallon: Megan Fox, Nick Cannon
Jimmy Kimmel: Chloe Grace Moretz
Craig Ferguson: Kelsey Grammer, Sloane Crosley
Seth Meyers: Clive Owen, Sarah Paulson
Jon Stewart: Wu-Tang Clan
Conan O'Brien: Lizzy Caplan, Sam Morril