Nicholas O. Tiron (died 1306 × 1307), Abbot of Arbroath and Bishop of Dunblane, was a late 13th-century and early 14th-century churchman in the Kingdom of Scotland. Little is known about Nicholas until he appeared on 21 November 1299, holding the position of Abbot of Arbroath in a charter of that abbey; the last attestation of his predecessor Henry can be dated to 16 October 1296, so that Nicholas must have become abbot sometime in between these two dates.