William Frost (died c. 1408), of York, was an English merchant and Member of Parliament (MP).

By October 1390, Frost had married Isabel Gisburn, a daughter and coheiress of the York MP and merchant John Gisburn and his wife, Ellen.

He was a Member of the Parliament of England for City of York in 1399. He was Mayor of York 3 February 1396–8, 1400–4, 3 June 1406 – 3 February 1407.^[1]