Louis James Moriarty (ルイス・ジェームズ・モリアーティ, Ruisu Jēmuzu Moriāti ) is the younger brother of William Moriarty . He is the one who manages and maintains all the Moriarty properties. 

Louis is depicted as a young man, rather tall, with red eyes and blond hair. He wears a pair of oval glasses, and he has a burn scar on his right cheek.
He wears a black outfit, consisting of a shirt, tie, frock coat, jacket, pants and a pair of shoes.

Louis is extremely devoted to his big brother.