Gossip Girl 8 p.m., Channel 56
I was a huge “Gossip Girl” fan until, about three years in, I wasn’t. Nighttime soaps often get tedious as the plot twists become increasingly absurd, desperate, and repetitive. “Revenge” is beginning to show symptoms of that syndrome. But as “Gossip Girl” ends its run on Monday night, it’s time to celebrate one of the first series to capitalize on social media and make it an essential and natural part of its story line. The two-hour finale will include a big reveal: the identity of Gossip Girl. My guess: Keyser Söze. Pictured: Leighton Meester (left) and Blake Lively.
Oh Yeah, That Happened 2012 9 p.m., TV Guide Network
The avalanche of year-end commentary is starting, and there are a few cultural artifacts that are inevitably going to dominate: Honey Boo Boo, “50 Shades of Grey,” and “Gangnam Style.” Among my personal favorites: Clint Eastwood’s “The Chair” (above). This special looks back on it all, including the TomKat breakup, which took the world by storm.
More Crazy Christmas Lights 10 p.m., DFH
Visual electric chair.
How I Met Your Mother 8 and 8:30 p.m., Channel 4
Patrice? “HIMYM,” you’ve got some splainin’ to do.
All About Christmas Eve 6 p.m., Lifetime
With Celeste Holm for the holidays?Matthew Gilbert can be reached at firstname.lastname@example.org. Follow him on Twitter @MatthewGilbert.