Gregory Rudolph Harts (born April 21, 1950) is an American former professional baseball player who played for the National League champion New York Mets in 1973.

[5] In spring training of 1973 he competed with Don Hahn, Rich Chiles and Dave Schneck to back up 42-year-old expected-starter Willie Mays in center field for the Mets, but ended up being sent down to the Blues before being recalled to the Mets in September.

[6][7][8][9] Harts made his Major League debut as a pinch hitter for the Mets on September 15, 1973 at Shea Stadium against the Chicago Cubs, batting for pitcher Buzz Capra.

[11][12] When the Mets moved into first place in the National League Eastern Division in late September for the first time and the large, jubilant home crowd started chanting, Mets' pitcher Tom Seaver said of him and young pitcher Bob Apodaca that "Some of these young kids were absolutely awed by the whole thing.

[14] Harts was outrighted to Tidewater at the end of the season, removing him from the Mets' 40-man roster.