Daniel Francis "Dashing Dan" Costello (September 9, 1891–March 26, 1936) was a Major League Baseball outfielder. Dan played for the New York Yankees and the Pittsburgh Pirates from 1913 to 1916. In 154 career games, he had 85 hits, 24 RBIs and a .286 AVG.. He batted left and threw right-handed. Costello was born in Jessup, Pennsylvania, and died in Pittsburgh, Pennsylvania.

Though listed as being in college from 1911-1914, he was already playing major league ball by 1913 with the New York Yankees. He was briefly in New York in early July, presumably after school ended, and then did the bulk of his work with the Pirates from 1914-1916.

Dan led the National League in pinch hits in 1915 with the Pittsburgh Pirates. He was a pinch-hitter almost as often as he played in the field, seeing his most action in 71 games in '15. Along with pitcher Al Mamaux, Dan became known for breaching curfew in pursuit of night life. In August, 1916, Pirates manager Jimmy Callahan had had enough and suspended Mamaux, and released Costello.

Dan was elected to the Mount St. Mary's University Sports Hall of Fame in 1979 for his achievements in baseball and basketball. In baseball, he served as a team captain for the Mount in his senior season (1914) and hit .388 for the Mountaineers in 1912. In Basketball, he was named to the All-Mountain team as a senior in 1914 after averaging 17.8 points in helping the Mount to a 13-4 record. He led the Mount in scoring his final three seasons.

(excerpted from Baseball Almanac, BR Bullpen & Wikipedia)