William Nassau Molesworth (8 November 1816 – 19 December 1890) was an English priest, historian and vegan.

He was the eldest son of John Edward Nassau Molesworth, vicar of Rochdale, Lancashire, and his first wife Harriet;[1] William was born 8 November 1816, at Millbrook, near Southampton, where his father then held a curacy.

[4] An earnest parish priest, in 1881 Molesworth was made an honorary canonry in Manchester Cathedral by Bishop Fraser.

After some years of ill-health, he died at Rochdale 19 December 1890, and was buried at Spotland.

[7] Molesworth was a vegan as he abstained from all animal products including butter, eggs and milk.

[4] Molesworth wrote a number of political and historical works, 'rather annals than history,' but copious and accurate.