William Townsend Mullins, 2nd Baron Ventry (25 September 1761 – 5 October 1827) was an Anglo-Irish politician and peer.
In this capacity, he was instrumental in securing the passage of the Irish Act of Union of 1800, for which his father was awarded a peerage.
He was married three times: firstly in 1784 to Sarah Anne Falkiner, youngest daughter of Sir Riggs Falkiner, 1st Baronet, and his only child by his second wife Anne Maturin.
He married secondly in 1790 Frances Sage, daughter of Isaac Sage; this marriage ended in 1796 with a divorce by Act of Parliament, by which both parties were free to remarry (Frances remarried Boyle O'Sullivan: she was also awarded a sum equivalent to her widow's jointure).
He left daughters, but no surviving male issue, and was succeeded by his nephew, Thomas de Moleyns, 3rd Baron Ventry.