Harold Dana Gregg (July 11, 1921 – May 13, 1991) was an American starting pitcher in Major League Baseball who played for the Brooklyn Dodgers (1943–47), Pittsburgh Pirates (1948–50) and New York Giants (1952).

In a nine-season career, Gregg posted a 40–48 record with 401 strikeouts and a 4.54 ERA in 827 innings pitched.

He had pitched very well in relief for Brooklyn, especially in the 4th game when Bill Bevens was hurling his 82⁄3 innings of no-hit ball only to lose in the 9th.

Since Brooklyn's manager had completely mishandled the pitching staff, continually using starters in relief, there was only Gregg ready to start game 7; Gregg thus joined some of the few but greatest pitchers in history who have started a World Series 7th game.

He threw 12 innings in the series with 10 strikeouts including DiMaggio, who seldom struck out.