The Bishop of Dunkeld is the ecclesiastical head of the Diocese of Dunkeld, one of the largest and more important of Scotland's 13 medieval bishoprics, whose first recorded bishop is an early 12th-century cleric named Cormac. However, the first known abbot dates to the 10th century, and it is often assumed that in Scotland in the period before the 12th century, the roles of both bishop and abbot were one and the same. The Bishopric of Dunkeld ceased to exist as a Roman Catholic institution after the Scottish Reformation, but continued as a royal institution into the 17th century. The diocese was restored (with a different boundary) by Pope Leo XIII on 4 March 1878; it is now based in the city of Dundee.
Dunkeld abbey was an offshoot of Iona, perhaps founded in the early 9th century, in the reign of Caustantín mac Fergusa, King of the Picts. It is not clear when its abbots got independence from the Abbots of Iona, but a notable event is the alleged transfer of the relics of Columba to Dunkeld during the reign of the Scoto-Pictish king Cináed mac Ailpín. Its abbots, like many Gaelic abbots of the period, took a strong role in secular affairs, hence the term "lay abbot". The following is a list of known abbots of Dunkeld; the list is not exhaustive.
While it is true that medieval churchmen took an active part in secular affairs (some fought in battles), that didn't make them in any sense "lay." They were still consecrated bishops or abbotts. A "lay abbott" was the secular lord of the abbey's lands. Since an abbey's property was often extensive, it was lucrative plum. Medieval monarchs enjoyed considerable authority over the church, and doubtless these positions were awarded to royal favorites.
The Bishopric of Dunkeld was one of the largest in medieval Scotland. However, in 1200, half of its territory was used to create the new Bishopric of Argyll.
In 1560 the Church of Scotland broke its ties with Rome.