William Wrigley Jr. (September 30, 1861–January 26, 1932) was a U.S. chewing gum industrialist. He was founder and eponym of the Wm. Wrigley Jr. Company in 1891. He was born in Philadelphia, Pennsylvania.

Wrigley played an instrumental role in the history of Catalina Island, off the shore of Los Angeles, California. He bought the island in 1919 and improved the island with public utilities, new steamships, a hotel, the Casino building, and extensive plantings of trees, shrubs and flowers. However, William Wrigley Jr.'s greatest legacy was his plan for the future of Catalina Island — that it remain protected for all generations to enjoy. He established the Catalina Island Conservancy for this, and he is honored with the Wrigley Memorial in the Wrigley Botanical Gardens on the island.

Wrigley was also owner of the Chicago Cubs baseball team, which held its annual spring training on Catalina Island. Wrigley Field, the Cubs' ballpark in Chicago, is named for the owner. The now-demolished former home of the Los Angeles Angels of the Pacific Coast League, at that time the Cubs' top farm team, was also called Wrigley Field. He purchased the Chicago Cubs from Albert Lasker in 1925.

The Arizona Biltmore Hotel in Phoenix, Arizona was partially financed, then wholly owned, by Wrigley, who finished the nearby Wrigley Mansion as a winter cottage in 1931. At 16,000 square feet it was the smallest of his five residences.

Wrigley left his fortune to daughter Dorothy Wrigley Offield, and son, P.K. Wrigley, who continued to run the company businesses for the next 45 years until his death.

His great-grandson William Wrigley, Jr. II is the executive-chairman and ex CEO of the Wrigley Company.