Alexander de Abernethy (after 1271 – c. 1315) was a Scottish baron. He was a son of and Maria de Ergadia. Alexander was a descendant of abbots of Abernethy; his great-grandfather , great-grandson of Gillemichael, Earl of Fife, was the first to style himself Lord (dominus) His daughter Margaret married John Stewart of Bonkyll, the new Scottish earl of Angus. They had issue: * , wife of John Stewart, 1st Earl of Angus. * , wife of (1) Sir Andrew de Leslie, and (2) Sir David de Lindsay.