Milligan Wetherall

Milligan is a man who was brainswept by Ledroptha Curtain, causing him to lose his memories. He later regains them, and then remembers that he is Kate Wetherall's father. He is almost always in disguise as something or other; in fact, he can change disguises in less than a minute, going from short and fat to tall and exceptionally thin. It's reasonable to believe, however, that he resembles Kate (or she resembles him), and we know for certain that he has blue eyes, is very tall, and has blond hair that is bright yellow. However, the books don't exactly mention his true name, for Milligan himself said the name "didn't feel right". At the end of The Mysterious Benedict Society, it is revealed that the name had popped into his head because of the last promise he had made to his daughter, going to the mill pond again.