Harry Potter's David Thewlis Originally Auditioned For A Worse Hogwarts Teacher

Despite the fact that David Thewlis has enjoyed a prolific acting career that spans more than 35 years across both film and television, for millions of fans worldwide, he will always be known as Remus Lupin from the "Harry Potter" franchise. Introduced in "Harry Potter and the Prisoner of Azkaban," Lupin joins the faculty at Hogwarts as the Defense Against the Dark Arts professor, quickly forming a bond with Harry Potter (Daniel Radcliffe) after the latter is attacked by dark creatures known as Dementors.

Longtime "Harry Potter" fans will know that Lupin's lessons were defined by their emphasis on dangerous magical creatures (memorably making the class tackle a shapeshifting monster called a boggart), which fits in nicely with the fact that Lupin himself is later revealed to be a werewolf. Considering the fact that three of Harry's other Defense Against the Dark Arts teachers attempt to either murder or torture him — and another tries to wipe his memory — it's safe to say that Lupin is the best of the bunch and Harry's favorite teacher by far throughout his time at Hogwarts, barring perhaps Rubeus Hagrid (Robbie Coltrane) in Care of Magical Creatures.

In spite of his abrupt departure at the end of the film, there's no question that Lupin is one of the most likable and knowledgeable teachers we get to know at Hogwarts, which is why it might surprise some fans to learn that David Thewlis actually auditioned for a much more sinister teacher before scoring the part of Lupin.

In a 2004 interview with Moviehole, David Thewlis revealed that he had actually auditioned for the part of Professor Quirrell in "Harry Potter and the Sorcerer's Stone" but lost out on the role to Ian Hart — who, ironically, later convinced him to take the role of Remus Lupin.

"I was up for the role of Quirrell in the first film, but Ian Hart got it," said Thewlis. "I was directing my own movie ['Cheeky'] when [the offer for Lupin] came through, and I'd actually cast Ian Hart in my movie so obviously I wasn't bitter. He said, 'Who're you playing'? And I said, 'Lupin,' and he said, 'Well, you gotta do it, that's the best part in the book.'"

Coincidentally, Professor Quirrell was also a Defense Against the Dark Arts professor, just like Remus Lupin — though "Harry Potter" fans will know that the similarities between the two characters stop there. Quirrell is a primary antagonist of the first movie, serving Lord Voldemort (Richard Bremmer) in his quest to steal the titular Sorcerer's Stone and trying to murder the 11-year-old Harry Potter along the way.

Fans who know Lupin from Thewlis' performance would be hard-pressed to imagine the actor taking on such a horrific and evil character within the "Harry Potter" franchise, though Thewlis has since played plenty of villains elsewhere, from 2017's "Wonder Woman" to "Enola Holmes 2" to Netflix's "The Sandman" adaptation. In any case, it's worth wondering what might have been if he'd taken on the shorter-lived role of Professor Quirrell — and whether another actor as Lupin would have captured the character's warmth the way that Thewlis did.