Bishop of Glasgow. Wishart was born into a Mearns family, Wishart was elected to succeed his uncle, William, as Bishop of Glasgow in 1271 and appears to have been consecrated in Aberdeen two years later. He ensured work continued on Glasgow Cathedral and was appointed one of the six Guardians of Scotland on the death of Alexander III. In 1290, he was involved in the negotiation of the marriage of the short-lived Margaret, Maid of Norway, to the son and heir of Edward I of England.
After John Balliol was appointed King of Scotland as a vassal of Edward, Wishart became central to the Council of Twelve tasked to regain independence and stand up to Edward. Despite having to swear allegiance on at least two occasions, Wishart also encouraged William Wallace and Robert Bruce to take up the cause. He was to absolve Bruce of the sin of killing Balliol and may well have placed the crown on Bruce's head in 1306. Later the same year Wishart was taken prisoner by Edward II, who asked the Pope Clement V to deprive him of office. Wishart was taken to Rome in 1308 and, although he was never removed from office, was kept there until 1311. He was finally released after the Battle of Bannockburn and returned to Scotland, where he died. He lies buried in Glasgow Cathedral.