Robert Blackadder was a medieval Scottish cleric, diplomat and politician, who was abbot of Melrose, bishop-elect of Aberdeen and bishop of Glasgow; when the last was elevated to archiepiscopal status in 1492, he became the first ever archbishop of Glasgow.
Robert was the younger brother of Patrick Blackadder of Tulliallan, a middling Fife laird. Robert studied at the University of St Andrews (where his name is listed among the students in either 1461 or 1462), and in 1464 he was received as a bachelor in the University of Paris. The following year, 1465, he graduated as licentiate. In 1471 King James III of Scotland sent him as a messenger to Pope Paul II. It was probably while at Rome that Robert secured from the pope the abbacy of Melrose. This was the first time a non-Cistercian had become abbot at Melrose, and moreover the pope granted Blackadder leave to take the abbacy without becoming a monk. This did not go down well with the monks at Melrose. One monk, Richard Lamb, challenged this decision at the papal court. Lamb had the support of the bishop of Glasgow, John Laing, and of the monks at Melrose. Several years of litigation followed, and after being offered a substantial pension, Blackadder resigned the abbacy in 1476. In 1477 Blackadder's name is recorded in a letter of Pope Sixtus IV, where it is said that the pope had received a petition from "Robert Blakidir", a rector of the church of Lasswade in the diocese of St Andrews, requesting permission to build a hospital near the church. Permission and funds were granted, and so came into being the Hospital of St Mary of Consolation. A year later, the pope granted Blackadder permission to convert the church of Lasswade into a prebend of the church of St Salvador in St Andrews, specifying that the holder must have a licentiate or doctorate.
He was elected as bishop of Aberdeen in sometime in 1480. The exact date of Robert's election to Aberdeen is uncertain, but at a meeting of the Lords of Council which took place between June 12 and June 23, he is named "Robert, bishop of Aberdeen". He does not seem to have been consecrated to the Aberdeen see before March 19, 1483, when he was translated to the then vacant bishopric of Glasgow. Blackadder travelled to Rome to receive consecration at the hands of Pope Sixtus IV. The consecration happened sometime in either May or June. By November 20 he is back in Scotland witnessing a royal charter at Edinburgh. Blackadder's trip to Italy had cost him a lot of money, and he fell heavily into debt. On March 31, 1487, a papal Bull was issued by Pope Innocent VIII granting Blackadder half of the diocese's benefices and ordering Blackadder's subordinates to pay a "benevolence", i.e. a tax, to pay back the debt.
Blackadder's reign as bishop of Glasgow is perhaps most noted for the elevation of the bishopric to archiepiscopal status. In 1472, a papal Bull of Sixtus IV elevated the Bishop of St Andrews to Archbishop. This was the first time any Scottish bishopric had received metropolitan status from the papacy. However, the move was not popular amongst the entire Scottish ecclesiastical establishment. The other bishops of Scotland resented having to do homage to the bishop of St Andrews, especially wealthier sees like Glasgow, Dunkeld and Aberdeen. It was Blackadder's predecessor at Aberdeen, Thomas Spens, who in February 1374 raised the first significant opposition by obtaining life-time exemption from the jurisdiction of St Andrews over either himself or his diocese. Nevertheless, on March 27, 1487 Innocent VIII made the archbishop of St Andrews "Primate of All Scotland". The latter was especially intolerable for the bishops of Glasgow, who would become subject to the visitations, inspections and the rule of St Andrews. The following year however, on March 25, 1488 an exemption was granted to Glasgow from this kind of interference from St Andrews, when this privilege was granted by the pope for Blackadder's own lifetime. However, this was still not enough. Moreover, Blackadder had the sympathy of the king, James IV, who himself was worried about so much power resting in the hands of one bishop. Letters to the pope were sent by the king and the Scottish parliament, requesting that Glasgow be given the same status as the Archbishopric of York. Finally, on January 9, 1492, a Bull of Pope Innocent VIII elevated Glasgow to an archbishopric, holding as suffragans the bishop of Dunkeld, the bishop of Dunblane, the bishop of Argyll, and the bishop of Galloway. Dunblane was reassigned to St Andrews while Blackadder was still archbishop, in 1500; Blackadder may have lost Dunkeld too, for we know that by 1515 Dunkeld is back within the jurisdiction of St Andrews.
Archbishop Robert was one of the leading figures of the regime of King James IV. Robert was involved in a number on embassies of James' behalf, including embassies to England, France and Spain. He arrived at the court of King Ferdinand II of Aragon and Queen Isabella of Castile on August 24, 1495. A letter, dated September 12 of this year, was written by these monarchs to the pope urging that Archbishop Robert be made Cardinal. Nothing seems to have come of it. Blackadder was back in Scotland by Christmas, but returned to Spain the following spring. His business was obtaining a bride for his king. The same business also took him to France. However, it was in England that a bride was eventually obtained, Margaret Tudor, the daughter of King Henry VII of England. Archbishop Blackadder would be made a godfather of their son James, the future King James V.
Archbishop Robert Blackadder died on July 28, 1508 while en route to Jerusalem on pilgrimage.