Who made the only unassisted triple play in World Series history?

Bill Wambsganss made the only unassisted triple play in World Series history.

The Cleveland Indians second baseman completed the feat in the fifth inning of Game 5 of the 1920 World Series against the Brooklyn Robins. With runners on first and second, Wambsganss caught Clarence Mitchell's line drive, stepped on second base to force out Pete Kilduff, and tagged Otto Miller as he tried to return from first.

Cleveland won the game 8–1 and eventually took the Series five games to two. The play remains unique because Wambsganss recorded all three outs himself, without a throw or assist from another fielder. It is also the only unassisted triple play in World Series or postseason history.

The game contained two other notable firsts: Elmer Smith hit the first grand slam in World Series history, and Cleveland pitcher Jim Bagby hit the first World Series home run by a pitcher in the modern era. Wambsganss played 13 major-league seasons, but the remarkable defensive play became his enduring legacy.