The seven major oil companies that dominated international petroleum after World War II were known collectively as the Seven Sisters. The phrase was popularized by Italian state oil company executive Enrico Mattei.
The group traditionally comprised Anglo-Persian Oil Company, Gulf Oil, Standard Oil of California, Texaco, Royal Dutch Shell, Standard Oil Company of New Jersey, and Standard Oil Company of New York. Several later changed names or became part of larger corporate groups.
Their influence came from control over exploration, production, refining, shipping, and marketing across many oil-producing regions. Their dominance weakened as producing countries created national oil companies and increased control over reserves, especially from the 1960s onward. The term is historical rather than the name of a formal organization.