Joshua Allen, 2nd Viscount Allen LLD (17 September 1685 – 5 December 1742) was an Irish peer and politician.
He was the son of John Allen, 1st Viscount Allen and succeeded to his father's titles on 8 November 1726. Between 1709 and 1727, he represented Kildare County in the Irish House of Commons.
He married Margaret du Pass on 18 November 1707. They had one child.