William Elmer Jacobs (August 10, 1892 – February 10, 1958) was an American pitcher in Major League Baseball from 1914 to 1927.

He played for the Philadelphia Phillies, Pittsburgh Pirates, St. Louis Cardinals, Chicago Cubs, and Chicago White Sox.

[1] Jacobs' key pitch was the curveball.

In 1926, he was suspended for 10 days after being caught with foreign substances on the mound.

This biographical article relating to an American baseball pitcher born in the 1890s is a stub.