"Oscar Acosta" redirects here. For the Major League Baseball pitching coach, see Oscar Carlos Acosta

Oscar "Zeta" Acosta (April 8, 1935 – disappeared 1974) was an American attorney, politician, novelist and activist in the Chicano Movement. He was most well known for his novels Autobiography of a Brown Buffalo (1972) and The Revolt of the Cockroach People (1973), and his friendship with American author Hunter S. Thompson. Thompson characterized him as a heavyweight Samoan attorney, Dr. Gonzo, in his novel Fear and Loathing in Las Vegas. Acosta disappeared in 1974 during a trip in Mazatlan, Mexico, and is presumed dead.