A ghost. And a mightily confused one, at that. This rather faded monkeyman in the furry loincloth haunts Lancre Castle, and the only available reason is that the castle was built on his burial mound. Thus, he is even farther behind the times than Lancre.
A 'Troglodyte' is any ancient person reputed to live in a cave, so Troglodyte Wanderer is what his name says; a wandering caveman.