Charles Oscar Finley (February 22, 1918–February 19, 1996), nicknamed Charlie O or Charley O, was an American businessman who is best remembered for his tenure as the owner of the Oakland Athletics Major League Baseball team. Finley purchased the franchise while it was located in Kansas City, moving it to Oakland in 1968.

Finley was born in Ensley, Alabama, but was raised in Gary, Indiana, and later lived in La Porte, a small town 60 miles east of Chicago. In 1946 he had a bout of tuberculosis that nearly killed him. Finley made his fortune in the insurance business, being among the first to write group medical insurance policies for those in the medical profession.

Finley showed a penchant for flair and inventive business practices. Sometimes, when wooing prospective customers, Finley would drive the client through the richest section of Gary. Pointing out a large mansion, Finley would declare "That's my place there, but I'm having it remodeled right now." Finley's fortunes grew and he ended up owning a 40 story insurance building in downtown Chicago. When Finley bought his personal property in Laporte, he hired John Mihelic as his ranch caretaker. The property was a working cattle ranch which consisted of an 18th century 11 room colonial manor house and 9 barns and various outbuildings. Finley had a large mansion built on the property which featured rounded portico's and columns which resembled the White House in Washington D.C. Mihelic and his family then moved into the original house and lived there as manager and caretakers.