Nicholas Altrock (September 15, 1876 – January 20, 1965) was an American professional baseball player and coach. He played in Major League Baseball as a left-handed pitcher between 1898 and 1919. After the 1919 season he continued to make periodic appearances as a pinch hitter for many years, until his final game at the age of 57. As a player, Altrock was a member of two World Series winning teams and then won a third World Series as a coach. He was a coach for the Washington Senators for many years.