Daniel Cornelius O'Connor (August 11, 1868 – March 3, 1942) was a Canadian Major League Baseball first baseman who played for the Louisville Colonels of the American Association in 1890. The 21-year-old rookie stood 6'2" and weighed 185 lbs. O'Connor played in 6 games for the Colonels, who won the 1890 AA pennant with a record of 88–44. His first appearance was on June 3 and his last on July 19. He hit .462 (12-for-26) with 5 runs batted in and 3 runs scored. At first base he handled 58 chances without an error and participated in 3 double plays.