Gulf Oil was a major American global oil company, in operation from 1901 to 1985. The eighth-largest American manufacturing company in 1941 and the ninth largest in 1979, Gulf Oil was one of the Seven Sisters oil companies. Prior to its merger with Standard Oil of California, Gulf was one of the chief instruments of the Mellon family fortune; both Gulf and Mellon Financial had their headquarters in Pittsburgh, Pennsylvania, with Gulf's headquarters, the Gulf Tower, being Pittsburgh's tallest building until the completion of the U.S. Steel Tower.
Gulf Oil Corporation (GOC) ceased to exist as an independent company in 1985, when it merged with Standard Oil of California (SOCAL), with both rebranding as Chevron in the United States. Gulf Canada, Gulf's main Canadian subsidiary, was sold the same year with retail outlets to Ultramar and Petro-Canada and what became Gulf Canada Resources to Olympia & York.