Gregory Sierra (born January 25, 1937) is an American actor known for his roles as Detective Sergeant Chano Amenguale on Barney Miller and as Julio Fuentes, the Puerto Rican neighbor of Fred G. Sanford on Sanford and Son (portrayed by Redd Foxx).

He also guest-starred as a Jewish radical in an unusually dramatic episode of All in the Family, working with the Hebrew Defense Association, an organization whose goal it was to stop antisemitism in the neighborhood. In the plot, he volunteers in helping to chase away neo-Nazi thugs presiding in the neighborhood who spray-painted a swastika on the Bunkers' front door. He is later killed by a car bomb planted by the neo-Nazis. The actor later went on to star as Dr. Tony Menzies on the unsuccessful sitcom A.E.S. Hudson Street.

His film credits include Beneath the Planet of the Apes (1970), Papillon (1973), The Towering Inferno (1974), The Prisoner of Zenda (1979) and The Trouble with Spies (1987). He also guest starred on many television series, including Mod Squad, Alias Smith and Jones, Mission: Impossible, Hawaii Five-O, Gunsmoke, The Greatest American Hero, Soap, Miami Vice, The Fresh Prince of Bel-Air, The X-Files, Murder, She Wrote and Hill Street Blues.

Sierra was cast as South American anti-Communist revolutionary "El Puerco" — whose friends simply call him "El" — on the serial spoof Soap, figuring prominently in the series' unresolved final episode in 1981. In 1984, he became a main cast member of the then-new TV drama Miami Vice where he played Lieutenant Lou Rodriguez; he asked to be written out of the series after just four episodes. More recently he had regular roles on the TV shows Zorro and Son, Something is Out There, and Common Law.

In 1992, Sierra played drug dealer Felix Barbossa in the Bill Duke-directed Deep Cover, which also starred Laurence Fishburne and Jeff Goldblum, and appeared in the comedy sequel Honey I Blew Up the Kid. The following year he played an Iraqi patrol boat captain in the comedy Hot Shots! Part Deux. He also played a man named Villanazul in the low-budget 1998 movie The Wonderful Ice Cream Suit. He also appeared as Corbin Entek in the Star Trek: Deep Space Nine episode "Second Skin".

Sierra is of Puerto Rican descent. He has performed with the National Shakespeare Conservatory in the New York Shakespeare Festival. He lives in Laguna Woods, California.