Daniel O'Leary (October 22, 1856 – June 24, 1922), also known as "Hustlin' Dan", was an American Major League Baseball player from Detroit. He played in the outfield sparingly for five seasons with five different teams from 1879 to 1884. The last season he played and managed the Cincinnati Outlaw Reds of the Union Association. O'Leary died in Chicago at the age of 65, and was buried at Mount Carmel Cemetery in Hillside, Illinois.