Tinsley Mortimer
Tinsley Mortimer CC '98 is a well-known New York socialite. In other words, she's famous for doing nothing but lounging about and attending expensive parties. Occasionally, she gives cringeworthy quotes to gossip reporters that will make you want to disavow either that she's a Columbia alum or that you yourself are in any way affiliated with the school.
While at Columbia, Mortimer earned her bachelors in Art History and was a member of secret society St. Anthony Hall, a fact which may have inspired the writers of Gossip Girl to install their characters at a fictional version of the club (Mortimer has made a cameo on the show, and has her own reality show on the same channel about "high society" in New York).