John Fenwick (baptised 17571823) was an English army officer, political radical and Irish nationalist writer. He was a close friend of William Godwin, a loyal associate of James Coigly, and the husband of Eliza Fenwick.
In mid-1801 Fenwick bought from Daniel Lovell a newspaper, the Albion and Evening Advertiser. He ran it with Charles Lamb, but publication ceased in August of that year. He had known Lamb through Godwin, from the previous year.
Fenwick wrote for Richard Phillips a biographical sketch of William Godwin, for Public Characters of 1799âÂÂ1800, from personal acquaintance, and asserting Godwin's personal fame of the period.