ISSAQUAH, Wash. — Jeff Brotman, cofounder of Costco Wholesale Corp. and the company’s chairman, died in his sleep at home on Tuesday. He was 74. Brotman helped build Costco into a global retailing powerhouse and was prominent in Puget Sound-area philanthropic and civic circles.

“The thoughts of Costco’s board, management and employees are with Jeff’s wife and family,” Costco said in a statement.

Brotman’s brother, Michel Brotman, told the Seattle Times that the cause of death was not immediately known and came as “a complete shock for everyone.” On the night before he died, Brotman attended a dinner for about 2,000 Costco warehouse managers from around the world who are gathered this week in Seattle, his brother told the newspaper.

Brotman and cofounder and former chief executive officer Jim Sinegal helped build Costco into one of the largest and most successful retailers in the world. The first Costco warehouse club opened in Seattle in 1983.

Costco currently operates 736 warehouses, including 511 in the United States and Puerto Rico, 97 in Canada, 37 in Mexico, 28 in the United Kingdom, 25 in Japan, 13 in Korea, 13 in Taiwan, eight in Australia, two in Spain, one in Iceland and one in France. Costco also operates electronic commerce websites in the United States, Canada, the United Kingdom, Mexico, South Korea and Taiwan.

Brotman grew up in a retailing family in Tacoma, Wash., where his father founded and ran a men’s apparel store.

Brotman was an early investor in Starbucks. He once told a reporter that he was convinced to back the coffee chain’s chief, Howard Schultz, by a combination of “the look in his eye” and the product, which he was already familiar with. “I was a Starbucks customer,” Brotman said. “And I’ve always felt you can build companies around great products.”

Brotman and his wife, Susan, were major donors and served as trustees of the Seattle Art Museum and have been major donors to Pacific Northwest Ballet.

Costco has not yet announced who will succeed Brotman as board chairman.