John Waddy (1751–1814) was an Irish stage actor and theatre manager.
Originally, intended for a career in law, he was acting at Dublin's Smock Alley Theatre by 1774, combining this with appearances at Irish and English provincial theatres.
He was then engaged by the Theatre Royal, Covent Garden in London making his debut there on 5 October 1796, under the management of Thomas Harris.
He particularly specialised in playing Stage Irishman and also took over many roles when John Quick left Covent Garden.
He departed from the Covent Garden company in 1810, and worked for a while at the Surrey Theatre south of the River Thames.