8:30 p.m., NBCMegan Mullally guest-stars as Ron's (Nick Offerman) ex-wife, Tammy, who wants to build a library in the pit. Cross your fingers for some Karen Walker sass.
9 p.m., FOXLance Reddick) past—in which people turn to ash—comes back to haunt him. Finally! More Broyles.
9 p.m., NBCJohn Krasinski) and Pam (Jenna Fischer) agree to double-date with Michael (Steve Carell) and his new girlfriend—Pam's mom (Linda Purl).
9 p.m., CWJared Padalecki) and Dean (Jensen Ackles) are stuck in an alternate TV universe—where they appear as characters in a forensics show, a sitcom, a medical drama.
9:30 p.m., NBCOur favorite anchorman Brian Williams guest-stars, and the tryouts for the newest TGS castmember continue.
10 p.m., FXkitten mittens.
Also on the airwaves ...
FlashForward, 8 p.m., ABC
Bones, 8 p.m., FOX
Survivor, 8 p.m., CBS
Community, 8 p.m., NBC
The Vampire Diaries, 8 p.m., CW
Grey's Anatomy, 9 p.m., ABC
CSI, 9 p.m., CBS
The Real Housewives of Atlanta reunion, 10 p.m., BRAVO
Private Practice, 10 p.m., ABC
The Mentalist, 10 p.m., CBS
The Real Housewives of Orange County, Season 5 premiere, 10 p.m., BRAVO
Project Runway, 10 p.m., LIFETIME
The League, 10:30 p.m., FX
What are you watching tonight?