William Melville (25 April 1850 – 1 February 1918) was an Irish law enforcement officer and the first chief of the British Secret Service Bureau.

William Melville was born into a Roman Catholic family in Direenaclaurig Cross, Sneem, County Kerry, the son of a baker and publican.

[1] In 1901 he worked with Gustav Steinhauer of the German Secret Service to thwart a plot against the Kaiser during the state funeral of Queen Victoria.

[1] In June 1900 Melville met future stage magician Harry Houdini when he came to Scotland Yard to showcase his abilities as an escapologist.

[5] According to the conclusions of author Andrew Cook, his biographer, which are not accepted by all historians, Melville then became the head of British Secret Service with the code name "M".