Walter Henry Ruether (September 13, 1893 – May 16, 1970) was an American baseball player who pitched for five different major league teams.

In his 11-year career, Ruether played for the Chicago Cubs, the Cincinnati Reds, the Brooklyn Robins, the Washington Senators, and the New York Yankees.

In the ninth-inning, White Sox shortstop Buck Weaver hit a 3-run home run off Ruether.

[5][7] Ruether parlayed his strong outing into a try-out with the Pittsburgh Pirates of the National League.

The contract stated that Ruether could opt out if the Pirates attempted to assign him to a Minor league farm team.

[9] After finishing the 1917 season, Ruether enlisted in the United States Army due to the break out of World War I.

On December 15 of that year, the Reds traded Ruether to the Brooklyn Robins in exchange for Rube Marquard.

The Yankees earned a spot in the 1926 World Series against the St. Louis Cardinals, and Ruether pitched in game three.

Ruether holds the National League record for most innings pitched in a season opening game.

He helped discover players such as Joey Amalfitano, Eddie Bressoud, Peanuts Lowrey and Mike McCormick.