Scholar and Scribe
Ultan was known as "Ultan the Scribe" for his work copying and illuminating manuscripts. He collected the writings of St. Brigid of Kildare, playing a role in preserving her memory. He also founded a school for poor students at Ardbraccan, and among his notable pupils were Broccán Clóen of Rostuirc and Tírechán, the hagiographer of St. Patrick.
His Latin hymn "Christus in nostra insula" is the most durable literary trace of his authorship, preserved in Solesmes chant tradition.