Mylotte was a hagsfiend. Mylotte's gender isn't known since he/she was merely mentioned, but Mylotte was said to be a powerful hagsfiend. An owl chieftain allied himself with him/her, and another hagsfiend under him, Hengen, lost one of his knights.
Mylotte is only mentioned in The First Collier and isn't seen or mentioned again. He/she either was killed in the battle or was led by Theo to the Middle Kingdom.