Clyde the Fog Spirit was first seen when Courage find a valuable love locket from the ground whilst he was digging. He wanted the love locket, or else, if the Bagge Family wouldnt return it, they would be cursed, seperated from their love ones.
After Courage gave the love locket back, Clyde then suddenly disspaears, however, Eustace ran to Clyde to get back the love locket.
During the ending of The Fog of Courage, Clyde re-appeared again when Eustace dug to get back the amulet.
In human form, he wears a black robe, has big eyes, nasty teeth and has a 19th century hairstyle.
In spirit form, his body parts were not seen except his face (excluding the hair) with fog covered around his face.