Harry Potter New TV Show: 25 Castings That Must Happen

David Thewlis was an excellent Remus Lupin without a doubt, although the films didn't utilize him enough after Prisoner of Azkaban. He needs a really great actor to play him, and Michael Fassbender is the man for the job.

During his peak in the 2010s, Fassbender was one of the finest actors in the business, and he absolutely killed it in pretty much every role he approached. He seems well-suited to the character of Lupin - he's got that sense of rugged, world-weary charm that the character needs - and he's a master at conveying turmoil brewing beneath the surface, as he proved in films like Shame.

On another note, it's hard to think of any actor in recent years who lost momentum like Fassbender did. He was everywhere just a few years ago, but he made a series of appallingly bad films in the mid 2010s, and these days, he's all but disappeared.

He really needs a great part to get his mojo back, and Remus Lupin could be just the ticket.