John Gustavus Handcock (1720 – 26 February 1766) was an Irish politician.
He was the sixth son of William Handcock and his wife Susan Warburton, daughter of Richard Warburton.[1] His older brother was William Handcock and his cousins were William Handcock, 1st Viscount Castlemaine and Richard Handcock, 2nd Baron Castlemaine.[1] In 1761, Handcock entered the Irish House of Commons, representing Ballyshannon until his death in 1766.[2]
On 6 August 1755, he married Margaret Caroline Wilson.[1] Their marriage was childless.[1]