Called "Hal" as a nickname, Halfast was born in TA 2972 (SR 1372) and was Sam's cousin and the son of Halfred Gamgee of the town of Overhill. He was known to have worked for the Boffin family as a hunter.
It was on one of his hunting jobs in the Northfarthing that he claimed to have seen a very large walking tree-like thing, that he called the Tree-men. People who knew him said that he was always seeing things and sometimes things that weren't there, and so many hobbits didn't believe that is what he really saw saying that it was really just an elm tree. If the report was true and he did see a walking tree, it may well have been an Ent however unlikely that might seem.