Missionary. Ternan seems most-likely to have been Scottish, a Pict from Aberdeenshire who was converted by St. Ninian's followers. He seems to have spent time in the priory founded by St. Ninian at Whithorn and then returned to Aberdeenshire, founding a small monastic settlement at Banchory and a church at Fordoun. His name is commemorated at Banchory-Ternan on lower Deeside, together with churches dedicated to him in Banchory, Muchalls, Arbuthnott and Collieston (the last long ruined). St Ternan's Well is also at Collieston. Some also suggest Ternan was associated with Culross Abbey in Fife.
Ternan's copy of Matthew's Gospel was said to have been enshrined in a metal case and remained in Banchory until the Reformation. His bell or Ronnecht was last recorded as having passed into the custody of Alexander Symson, the minister of Banchory-Ternan, in 1491. During excavations for the railway in 1863 an old bronze bell was found which now hangs on the front wall of Banchory Ternan East Church.