John Ap-Adam III, 1st Baron Ap-Adam (died May 1311) was created baron by writ in 1299.

The first baron served in the Scottish wars. On July 22,1298, he served in the battle of Falkirk and was knighted and borne his coat of arms afterward.

Ap-Adam married Elizabeth de Gurnay, the daughter of John de Gurnay Baron of Beverstone, and Olivia Lovel. They had at least one son, Sir Thomas Ap-Adam, who left issue.

This Thomas was never summoned to parliament; thus the barony became dormant.