James Leslie "Hippo" Vaughn (April 9, 1888 – May 29, 1966) was an American left-handed pitcher in Major League Baseball.

In a career that spanned thirteen seasons, he played for the New York Highlanders (1908, 1910–1912), the Washington Senators (1912), and the Chicago Cubs (1913–1921).

His highlight year was 1918, where he earned a National League-leading 22 wins when the season was ended a month early due to government restrictions brought about by World War I.

[1] He began his career in baseball in 1906 in the Texas League, playing for the Temple Boll Weevils.

[7] He pitched a shutout in his next appearance nine days later against the Washington Senators in a shortened six inning effort, although the game ended with a scoreless tie.

The following year, he was selected to pitch the Opening Day game for the Highlanders, this time in Shibe Park against the defending World Series champion Philadelphia Athletics and Chief Bender.

He pitched a complete game while allowing one run on four hits with three strikeouts and one walk while earning a 2–1 win.

Vaughn appeared for the final two outs of the Opening Day game against the Boston Red Sox, pitching in relief of Ray Caldwell.

He made seven appearances with the team, the first being a four inning effort on August 22 against the New York Giants, where he allowed three hits and four runs.

He finished in the top ten of the National League in numerous categories, such as 4th in ERA, 7th in wins, 3rd in strikeouts, but also 4th in walks, 2nd in wild pitches with 13, and 1st in errors.

At the ballpark now known as Wrigley Field, Vaughn dueled with Fred Toney of the Cincinnati Reds for nine hitless innings.

Toney continued to hold the Cubs hitless in the bottom of the inning, winning the game for the Reds.

With changes to the scoring rules in recent years, this game is no longer considered as a no-hitter for Vaughn, but is still the only occasion in major league history nine innings were played without a hit between both teams.

His final two batters, Frank Snyder and pitcher Phil Douglas, each hit home runs off him.