Ulick Fionn Burke, 6th Clanricarde or Mac William Uachtar (English: /ˈjuːlɪk ... klænˈrɪkɑːrd/ YOO-lik ... klan-RIK-ard; died 1509) was an Irish chieftain and noble.

[3] Burke was an especially aggressive warlord, and sought to impose his authority over not only his fellow Bourkes in north Connacht, but over the Ui Maine, the Síol Muireadaigh and the independent towns of Athenry and Galway.

Felim Finn O'Conor repaired to these armies, and gave himself up into the hands of O'Donnell, in behalf of his territories and chieftains.

The sons of Felim Finn O'Conor (i.e. Hugh, Turlough, and Conor) passed by them to Baile-tobair-Bhrighde, which they burned and plundered.

To make matters worse, Burke entered into a successful alliance with Toirdhealbhach Donn Ó Brien, King of Thomond.

Early in 1503, Mac William of Clanrickard gave a very great overthrow to O'Kelly and a party of the people of Conmaicne-Cuile, where the greater part of the gallowglasses of both the Clann-Donnell and Clann-Sweeny were slain around their constables, and where Walter, the son of John Burke, a distinguished captain, was also slain.

FitzGerald had a similar motive, in that his daughter was being slighted by the affair, but, with Burke's capture of the independent towns of Athenry and Galway, the matter had become national and could no longer be ignored.