Jeremy Samuel Piven (born July 26, 1965) is an American actor. He is best known for his role of Ari Gold in the hit HBO series, Entourage, for which he has won the Emmy Award for Best Supporting Actor on three occasions and a Golden Globe Award.

Piven was born in Manhattan and grew up in Evanston, Illinois, a suburb north of Chicago. He graduated from Evanston Township High School, and attended Harand Theater Camp in Elkhart Lake, Wisconsin, as a teenager. He played the part of "Bernardo" in West Side Story, there. In Illinois, he trained at Piven Theatre Workshop, founded by his parents Byrne Piven and Joyce Piven, both of whom were actors and drama teachers. He also attended Drake University in Des Moines, Iowa, and is a member of the Pi Kappa Alpha Fraternity. He spent a semester at the National Theater Institute in Waterford, Connecticut. He has appeared in a number of films with John Cusack, who is also from Evanston and is a fellow alumnus of the Piven Theatre Workshop (as are Cusack's sisters Joan and Ann). Piven and Cusack once shared an apartment and have been friends since high school.

Piven's first significant role was as a regular cast member for several seasons on HBO's The Larry Sanders Show, where he played the head writer Jerry. Piven has appeared in several successful films, including Lucas, Grosse Pointe Blank, Singles, Very Bad Things, The Family Man, Black Hawk Down, Heat, PCU, Old School, Rock N Rolla, Smokin' Aces and Runaway Jury. He also had brief cameo appearances in Rush Hour 2 and in the US release of Cars.