Jessi Ruth Klein is an American writer, actress, and stand-up comedian from New York City. Born on August 18, 1975, she has made regular appearances on shows such as The Showbiz Show with David Spade and VH1's Best Week Ever, and performed stand-up on Comedy Central's Premium Blend. She also provided commentary for CNN during the debates of the 2004 presidential election.

A self-proclaimed "geek", Klein has appeared on television specials such as My Coolest Years: Geeks on VH1 and Rise of the Geeks on E!. She gave voice to the character Lucy in the animated pilot for Adult Swim's Lucy, the Daughter of the Devil.

Klein previously worked as the director of development for Comedy Central, where she helped develop shows such as Chappelle's Show and Stella. She was the head writer and executive producer of Inside Amy Schumer.