American insurance executive and professional baseball club owner who was frequently involved in controversy with the commissioner of baseball, the American League, managers, and players. His Oakland Athletics won three consecutive World Series (1972–74).

Finley was a farm boy who loved baseball, and after he moved with his family to Gary, Indiana, and went to work in a steel mill, he organized the Gary Merchants in an Indiana-Michigan industrial league. During World War II, he worked in a defense plant and showed an aptitude for selling, which he later pursued full-time. While hospitalized with tuberculosis (1946–48), he planned a new group insurance coverage for physicians and formed his own company, becoming a millionaire in two years.

Finley started looking for a baseball franchise in 1954, and in 1960 he bought the Kansas City Athletics of the American League. Finley became known for his flamboyant marketing, and in an era of white and gray uniforms and traditional black shoes, he dressed the Athletics in green and gold uniforms and white shoes, and behind home plate he installed a mechanical rabbit that popped out of a hole and gave umpires fresh baseballs. After falling out with civic leaders, he moved the Athletics to Oakland, California, in 1968, where he outraged traditional owners with such promotions as hot-pants nights and cow-milking contests. Later he introduced a mule, Charlie O., as a mascot. Some of the lasting baseball innovations Finley championed included the playing of postseason games at night to accommodate larger television audiences and the American League's use of the designated hitter position (a player whose only role is to bat for the pitcher). In his ownership career (1960–80), he had 18 managers, some of them twice. After his World Series successes, attendance fell off, and the city of Oakland sued him for not promoting the club. Attendance revived with his last manager, Billy Martin, but Finley sold the club in 1980.