The name Cillian was borne by several early Irish saints including missionaries to Artois (France) and Franconia (Germany) and the author of the life of St Brigid.
[1] The name is said to derive from Saint Kilian, an Irish missionary to Germany in the 7th century, who, according to the Acta Sanctorum, was born in Mullagh, County Cavan, Ireland c. 640.
He departed for his mission to the continent with 12 apostles from Kilmacologue in the parish of Tuosist, County Kerry, Ireland.
[2] In 689, he was martyred in Würzburg, now in Bavaria, and subsequently became the city's patron saint.
[3] Patrick Woulfe wrote that Cillian is a diminutive of Ceallach which means 'war', 'strife', or 'bright-headed'.