William Hennessy

William Hennessy may refer to:


 * Bill Hennessy (Cork hurler) (1882–1954)
 * Bill Hennessy (Kilkenny hurler) (born 1968)
 * William Hennessy (violinist), Australian classical violinist
 * William C. Hennessy, American civil servant and political figure
 * William John Hennessy, Irish artist
 * William Maunsell Hennessy, Irish official and scholar