Harry Potter New TV Show: 25 Castings That Must Happen

Horace Slughorn, who was beautifully played by Jim Broadbent in the films, is very much a tragic, comic figure. He provides plenty of humour, but there's also a lot of pathos to the character due to his guilt over telling Voldemort what a horcrux is during his time at Hogwarts. The role needs an actor who can be very funny while also bringing a lot of emotional depth, and few actors would be better-suited to this than John Goodman.

By far one of the industry's most versatile and reliable character actors, Goodman has always shone equally bright in both his comedic and dramatic roles, as he's proven in things like Barton Fink, 10 Cloverfield Lane, and Black Earth Rising.

He looks the part more than Broadbent did as well - Slughorn is described as being a larger man in the books - and even though he's American, they could always make Slughorn an American wizard.