Costco Wholesale Corporation, trading as Costco, is an American multinational corporation which operates a chain of membership-only warehouse clubs.

Costco's history began with Sol Price and his son, Robert, opening the first Price Club warehouse on July 12, 1976, on Morena Boulevard in San Diego, California, thus giving birth to a new concept: a retail warehouse club. The Price family placed Price Club Warehouse #1 inside a series of old airplane hangars previously owned by Howard Hughes; that warehouse, now known as Costco Warehouse #401, is still in operation today.

Costco acts as an investment broker and travel agent. Costco has an agreement with Ameriprise for auto and home insurance. In 2004 Costco offered an original artwork by artist Pablo Picasso on their online store; more recently[when?] a highly regarded 1982 Mouton Rothschild wine was offered as well as other rare wines in rotation.

Costco's worldwide headquarters are in Issaquah, Washington, but the company opened its first warehouse in nearby Seattle in 1983. Through mergers, Costco's corporate history dates back to 1976, when its former competitor Price Club was founded in San Diego, California.

As of August 23, 2018, Costco had a total of 759 warehouses; in the United States (527), Canada (100), Mexico (38), United Kingdom (28), Japan (26), South Korea (15), Taiwan (14), Australia (9), Spain (2), Iceland (1) and France (1).

Costco ranked #15 on the 2017 Fortune 500 list.