Wormtail, also known as Peter Pettigrew, is a character from the Harry Potter series created by J.K. Rowling. He is a former friend of James Potter and Sirius Black and is known for his ability to transform into a rat. Wormtail is often depicted as cowardly and self-serving, ultimately betraying his friends to serve the dark wizard Lord Voldemort. In the series, Wormtail plays a crucial role in the return of Voldemort, helping him regain his physical form. His actions lead to significant consequences for the main characters, particularly Harry Potter. Despite his small stature and timid nature, Wormtail's choices have a lasting impact on the story's events.