Recasting characters in movies and TV shows is a very common thing. There are plenty of reasons why it happens. It could be because the actor is no longer able to portray that character, or, in the most unfortunate cases, such as Paul Walker, the actor can be deceased.
A classic example for recasting actors is Harry Potter. You will be surprised to find that quite a big number of characters were portrayed by different people throughout the franchise, specifically these 8 characters.
Obviously. In the first two movies from the series, Richard Harris portrayed Dumbledore. However, because the actor passed away after Chamber of Secrets, Michael Gambon was cast for the role instead.
Source:A For Anything
From The Goblet of Fire to the end of the series, the noseless villain was portrayed by Ralph Fiennes.
In the movies preceding The Goblet of Fire, Voldemort had a nose and was portrayed by Richard Bremmer. This was the Voldemort that was on the back of Professor Quirell’s head, for those that don’t know.
Source: Twitter | @PotterHistories
3. Cedric Diggory
Before his Twilight days, Robert Pattinson found himself portraying Cedric Diggory in the movies, except that he made another appearance in the series portrayed by a totally different actor.
Cedric was the seeker in the Quidditch match between Gryffindor and Hufflepuff, where he was portrayed by a totally different actor that no one knows the identity of.
4. Bill Weasley
This guy was portrayed by Domhnall Gleeson in both Deathly Hallows parts. He also appeared in previous movies in a moving photograph, where a different actor played him.
Source:Harry Potter Wiki
Specifically, in this photo of the Weasleys on vacation in Egypt, where he is played by Richard Fish.
Source:Harry Potter Wiki
5. The Fat Lady
In The Prisoner of Azkaban, this underrated character was played by Dawn French.
Source: Twitter | @PotterWorldUK
But it was originally Elizabeth Spriggs that played this character in Sorcerer’s Stone.
Griphook was played by Warwick Davis in Deathly Hallows. But his first appearance was actually in Sorcerer’s Stone…
…where he was played by Verne Troyer.
7. Hermione’s dad
Remember that scene in Deathly Hallows where Hermione had to wipe her parents’ memory of her? In that scene, her father was portrayed by Ian Kelly.
But her father appears in the Chamber of Secrets, where he is played by Tom Knight.
8. Tom the bartender
The bartender of the Leaky Cauldron in Prisoner of Azkaban was played by Jim Tavare, where he was a bit younger and more hunchbacked.
In the first movie he is played by Derek Deadman, and the only possible explanation is reverse aging.