| Andrew Jeffrey Gunion Barclay | |
| Birth Date: | 19 April 1849 |
| Birth Place: | Hawick, Roxburghshire |
| Death Place: | London |
| Resting Place: | Saint Andrews Churchyard in Aldringham |
| Resting Place Coordinates: | 52.1862°N 1.5851°W |
| Spouse: | Jane Pender |
| Parents: | George and Jane Barclay |
| Field: | Mathematics |
| Work Institutions: | George Watson's College High School of Glasgow |
| Alma Mater: | University of Edinburgh |
| Known For: | Founder of Edinburgh Mathematical Society |
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. He retired in 1914 and went to reside in London with a son.
Barclay, with Alexander Yule Fraser and Cargill Gilston Knott, issued in January 1883 a circular calling for a Mathematical Society. That year the Edinburgh Mathematical Society was founded and Barclay became its president in 1884.