Sir William Lewis Salusbury-Trelawny, 8th Baronet (4 July 1781 – 15 November 1856), was a British politician.

Born William Trelawny, he assumed in 1802 the additional surname of Salusbury.

He served as High Sheriff of Cornwall in 1811[2] and later sat as member of parliament for Cornwall East from 1832 to 1837.

Salusbury-Trelawny died in November 1856, aged 69.

He had married in 1807 Patience Christian Carpenter; they had several children.