In baseball, an unassisted triple play occurs when a defensive player makes all three outs by himself in one continuous play, without his teammates making any assists. Neal Ball was the first to achieve this in Major League Baseball (MLB) under modern rules, doing so on July 19, 1909. For this rare play to be possible there must be no outs in the inning and at least two runners on base, normally with the runners going on the pitch. An unassisted triple play usually consists of a hard line drive hit directly at an infielder for the first out, with that same fielder then able to double off one of the base runners and tag a second for the second and third outs.

Cornelius "Neal" Ball was an American baseball shortstop who played seven seasons in Major League Baseball (MLB). He played for the New York Highlanders, Cleveland Naps, and Boston Red Sox from 1907 to 1913. Although his primary position was shortstop, Ball played at second base, third base, and in the outfield as well. He is the first player to turn an unassisted triple play in Major League Baseball history on July 19, 1909.