Aaron Karo is a stand-up comedian and author of Ruminations on College Life and Ruminations on Twenty-Something Life, both of which originated from his e-mail based column "Ruminations".

The column started in 1997 when Karo was a freshman at the University of Pennsylvania. Originally taking on the form of various observations on college life and being e-mailed to roughly 20 friends, it grew in popularity among college students by word of mouth and constant e-mail forwards; a mailing list was created later that year, with over 45,000 subscribers by Karo's graduation.

He also makes regular contributions to the website CollegeHumor.com.