Viscount Bulkeley, of Cashel in the County of Tipperary, was a title in the Peerage of Ireland. It was created on 19 January 1644 for Thomas Bulkeley, the son of Sir Richard Bulkeley of Beaumaris and a supporter of King Charles I of England. The title descended from father to son until the death of his great-great-grandson, the fifth Viscount, in 1738. The late Viscount was childless and was succeeded by his younger brother, the sixth Viscount. The latter was succeeded by his son, the eighth Viscount. He was created Lord Bulkeley, Baron of Beaumaris, in the County of Anglesey, in the Peerage of Great Britain on 14 May 1784, which entitled him to a seat in the House of Lords. In 1802 he assumed by Royal license the additional surname of Warren, which was that of his father-in-law, Sir George Warren. On his death in 1822 both titles became extinct. Sir Richard Bulkeley Williams, 10th Baronet, of Penrhyn, succeeded to the Bulkeley estates and assumed by Royal license the additional surname of Bulkeley (see Williams-Bulkeley Baronets).
From the second to the sixth viscount, all viscounts were Members of Parliament.