William Wharton Cassels (11 March 1858 – 7 November 1925) was an Anglican missionary bishop.

Cassels was born in Oporto, Portugal, the sixth son of John Cassels, a merchant, and Ethelinda Cox, a distant relation of Warren Hastings.

A member of the famous ‘Cambridge Seven’,[7] he joined the China Inland Mission in 1885, together with Arthur T. Polhill-Turner and Montagu Proctor-Beauchamp, the three established a proper Church of England diocese in Szechwan.

Cassels married Mary Louisa Legg, daughter of Edward Legg, at Holy Trinity Cathedral in Shanghai, on 4 October 1887.

[13] He had a son Harold Cassels born in Szechwan.