Andrew Jeffrey Gunion Barclay (19 April 1849 – 15 September 1943) was a Scottish mathematician, known for being one of the founders of the Edinburgh Mathematical Society.

Barclay studied at University of Edinburgh where he graduated in mathematics in 1880.

[1] Then he was professor of mathematics at George Watson's College (Edinburgh) and at High School of Glasgow.

Barclay, with Alexander Yule Fraser and Cargill Gilston Knott, issued in January 1883 a circular calling for a Mathematical Society.

[3] That year the Edinburgh Mathematical Society was founded and Barclay became its president in 1884.