William Joseph Castling (1838 – 7 June 1906) was a member of the Queensland Legislative Assembly.

He arrived at Dalrymple, Queensland in 1863 and worked the goldfields in the area before purchasing a half share in a Townsville wholesale butchery in 1876 which by 1880 employed 40 people.

Castling drowned in Ross Creek in Townsville in June 1906[1] and was buried in the West End Cemetery.

[2] Castling won the junior position in the two-member seat of Townsville for the Ministerialists at the 1896 Queensland colonial election.

[3] He represented the electorate for three years and did not stand at the 1899 Queensland colonial election.