This interesting surname is of Scottish and Irish origin, and is an Anglicized form of the Gaelic personal name 'Sitheach', probably originally a byname from the adjective 'sitheach', relating to fairies, eerie, mysterious. The name was first established in Ireland by a branch of the Scottish McDonnell's, descended from Sithich, great-grandson of Domhnaill, who came to Ireland early in the 14th Century. The surname is now peculiar to Munster, though it is not found there before 1420, when the first of the family came to County Limerick, where they took service with the Earl of Desmond and established themselves near the town of Rathkeale. The modern surname can be found as (Mac)Sheehy, Sheekey, Sheach and Se(a)th. Among the recordings in Ireland are the christenings of William, son of Silvester and Mary Sheehy, on April 29th 1752 at St. Mary's Cathedral, County Limerick, and of Michael, son of Edmund Sheehy and Dorothy Allen, on June 29th 1796 at Killarney Roman Catholic Church, County Kerry. The first recorded spelling of the family name is shown to be that of Sheehy, which was dated 1420, County Limerick, Ireland, during the reign of King Henry V of England, known as 'The Victor of Agincourt', 1413 - 1422. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.