Remus John Lupin is a fictional character in the Harry Potter book series written by J. K. Rowling. He first appears in Harry Potter and the Prisoner of Azkaban as the new Defence Against the Dark Arts professor. Lupin remains in the story following his resignation from this post, serving as a friend and ally of the central character, Harry Potter. In the films, he is portrayed by David Thewlis as an adult, and James Utechin as a teenager.

Harry Potter is a series of seven fantasy novels written by British author J. K. Rowling. The novels chronicle the lives of a young wizard, Harry Potter, and his friends Hermione Granger and Ron Weasley, all of whom are students at Hogwarts School of Witchcraft and Wizardry. The main story arc concerns Harry's conflict with Lord Voldemort, a dark wizard who intends to become immortal, overthrow the wizard governing body known as the Ministry of Magic, and subjugate all wizards and Muggles.