William Longworth (26 September 1892 – 19 October 1969) was an Australian freestyle swimmer who competed for Australasia in the 1912 Summer Olympics.

Longworth attended Sydney Grammar School, where he excelled in athletics, swimming, and rugby.

[2] In January 1911, he won the 1320-yard freestyle in world record time at the Australian Championship by 30 yards.

[2] In 1912, he won all the New South Wales and Australian freestyle championships from 100 yards to one mile.

[2] He served in France from November as a sergeant with the Anzac Entrenchment Battalion.