John Plunkett, 3rd Baron of Dunsany

John Plunkett, 3rd Baron of Dunsany (died 1500) was an Anglo-Irish nobleman.

He was the only son of Richard Plunkett, 2nd Baron of Dunsany, and his wife Joan FitzEustace, daughter of the wealthy and powerful statesman Rowland FitzEustace, 1st Baron Portlester. He succeeded to the title around 1480.

In 1474 he was a founder member of the Brotherhood of Saint George, a short-lived military guild which was charged with the defence of the Pale (the only part of Ireland under secure English control), and which was for some years the only English standing army in Ireland.

In 1487, like the great majority of the Anglo-Irish nobility, he made the mistake of supporting the claims of the pretender Lambert Simnel to the English throne. Simnel was crowned in Dublin, and invaded England with a largely Irish army, but his cause was crushed at the Battle of Stoke.

The victorious King Henry VII, founder of the Tudor dynasty, was magnanimous in victory. Lambert was pardoned, and Dunsany and his fellow peers in 1488 performed an act of public penance for their rebellion and in their turn also received a royal pardon. The King however could not resist playing a joke by inviting some of them, including Dunsany, to a banquet at Greenwich in 1489 where to their embarrassment Simnel, now a servant in the royal kitchen, waited on them at table.

Dunsany attended the Parliament of Ireland in 1490 and 1493. He was fined for his non-attendance at the Parliamentary session of 1498.

Dunsany married Catherine Hussey, daughter of John Hussey, 7th Baron Galtrim, with whom he had three children, Edward, Nicholas and Margaret. He died in 1500 and was succeeded by his eldest son Edward Plunkett, 4th Baron of Dunsany.