William Mellish (c.1710 – 16 December 1791) was a British government administrator and Member of Parliament.
He was born the second son of Joseph Mellish of Doncaster, Yorkshire and Blyth Hall, Nottinghamshire and was educated at Eton School (1725) and Peterhouse, Cambridge (1726).
He was appointed a Commissioner of Excise for 1751-1760 and Receiver General of Customs from 1760 to January 1763 and from 1765 to 1786.
Mellish was elected the Member of Parliament for East Retford from 1741 to 18 December 1751.
This article about a Member of the Parliament of Great Britain (1707–1800) representing an English constituency is a stub.