Grimesby Roylott is a fictional character from Sir Arthur Conan Doyle's Sherlock Holmes stories. He appears in "The Adventure of the Speckled Band," where he is depicted as a violent and aggressive man. Roylott is a former doctor who has a troubled past and a strong desire for wealth, which drives him to commit heinous acts. In the story, Roylott is the stepfather of Helen Stoner, the main character, and he seeks to eliminate her to gain her inheritance. His character is notable for his use of a trained snake, which he employs as a murder weapon. Roylott's actions ultimately lead to his own demise, showcasing the themes of justice and retribution in the narrative.