William Ellam Allen (1880–1960) was an acting director of the U.S. Bureau of Investigation (BOI) during 1919.

The BOI was a predecessor of the Federal Bureau of Investigation (FBI).

[1] A former assistant in war matters to the chief of the Bureau of Investigation, Allen was appointed acting director on February 10, 1919.

[1] Allen resigned the post from June 30, 1919, and was replaced by William J.

This United States biographical article related to crime is a stub.