Who wrote the surviving seventh-century Vita sancti Patricii about Saint Patrick?

Muirchú moccu Machtheni wrote the surviving seventh-century Vita sancti Patricii about Saint Patrick.

Muirchú was a monk and historian associated with Leinster. His Life of Saint Patrick is one of the earliest surviving biographies of the Irish saint and was probably composed in the later seventh century at the encouragement of Aedh, bishop of Sletty. Muirchú and Aedh were both associated with the Synod of Birr in 697.

The Vita is a hagiography, meaning a saint's life written to present religious meaning as well as biography. It portrays Patrick as a powerful missionary who confronts rulers, druids, and pagan practices. Because it was written roughly a century and a half after Patrick's lifetime, it is not treated as a straightforward eyewitness account.

Muirchú's work is often confused with Tírechán's near-contemporary Collectanea. Both writers produced seventh-century accounts of Patrick and drew on earlier material, including the lost Book of Ultán. Bede was an English historian writing later, and Ultán was a source associated with the tradition rather than the author of this Vita.