John Barclay (1758-1826) was one of the most distinguished, respected and enthusiastic teachers of anatomy in Edinburgh during the first decades of the 19th century. He taught this subject in the extra-mural school from 1797 until 1825. He initially studied divinity at St Andrews University, intending entering the Church. After acting as a minister of the Church for about 10 years and tutoring for most of these years, he decided to study medicine in Edinburgh, and was particularly attracted to anatomy. After he qualified with the MD degree, he proceeded to London where he attended the anatomical classes of Dr Marshall for about a year. On his return to Edinburgh he taught anatomy to a small class for three years in High School Yards. He then acquired a property at Number 10 Surgeons' Square where he taught from 1800 until 1825, when he was forced to withdraw due to poor health. His lectures were meticulously prepared, and his illustrations clear and copious. In 1804, his class was recognised by the Royal College of Surgeons of Edinburgh as fulfilling their requirements for students who wished to take the College's examinations. During the winter sessions he taught anatomy, physiology and surgery, while in the summer sessions he taught comparative anatomy, a subject in which he was particularly interested. He was elected an Honorary Fellow of the Royal College of Surgeons of Edinburgh in 1821. His classes were taken over by his partner Robert Knox, at that time Conservator of the College's Museum.