William "Willy" Brennan was an Irish highwayman. He was a Waterford man but carried out most of his exploits in County Tipperary. He was betrayed by a comrade for the price on his head and was hanged in Clonmel Gaol in County Cork in 1809. Not much is known about him except a lot of legends that built him into a Robin Hood figure. The earliest version of the ballad dates to the middle 19th century, and various versions of the song were extant in Ireland, Great Britain, Canada and the United States. The song's writer is unknown. It was introduced to Folk Revival audiences by Burl Ives who recorded it in 1949 for his LP Wayfaring Stranger (The Burl Ives Songbook, 1953), Ed McCurdy in 1955, The Clancy Brothers and Tommy Makem and The Kingston Trio. I learned it from the Clancy's recording.