William Powell (1735–1769) was an English actor.
He was born in Hereford, and educated at Hereford grammar school and at Christ's Hospital in London. Sir Robert Ladbrooke, a distille and then president of Christ's Hospital, took him on as apprentice in his counting-house. Powell, however, was interest in amateur theatricals: Ladbrooke suppressed a club in Doctors' Commons of which Powell had become a member. For a while Powell remained in Ladbrooke's office. Charles Holland however, introduced him to David Garrick, who wanted to travel and sought a substitute actor.
Carefully coached by Garrick, Powell made his first appearance on stage at Drury Lane Theatre on 8 October 1763 as Philaster (in an adaptation of Beaumont and Fletcher's play, by George Colman the Elder). Supported also by James Lacy, Powell made a success. The ticket receipts were up to the best Garrick days.
Garrick reappeared in the season of 1765–6, and took over from Powell a few characters; Powell added to his repertory. In 1767 Powell joined Thomas Harris, John Rutherford, and Colman in purchasing John Rich's patents for Covent Garden Theatre. Powell was at this time bound for three years to Drury Lane under a penalty of £1,000, while his borrowed share of the purchase-money was £15,000.
Powell became a favourite in Bristol, where, at the Jacob's Well Theatre, on 13 August 1764, he took his first benefit as King Lear. On the erection of the King Street Theatre, the foundation-stone of which was laid on 30 November 1764, Powell became associated with two local men, Arthur and Clarke. The lease of the theatre was for seven years. On 30 May 1766 it opened with The Conscious Lovers, given gratis since the license had not yet been obtained, with Powell as Young Bevil. The Citizen (Arthur Murphy) with James William Dodd was also given. A prologue, written by Garrick, was spoken by Powell.