William Sidney (disambiguation)

William Sidney, 1st Viscount De L'Isle (1909–1991), was the Governor-General of Australia.

William Sidney may refer to:
 * William Sidney (MP for Sussex), MP for Sussex in 1429 and 1433
 * Sir William Sidney (1482?–1554), English courtier under Henry VIII and Edward VI
 * William Sidney, 5th Baron De L'Isle and Dudley, candidate in the 1944 Chelsea by-election