Harry Potter: 10 Worst Characters Introduced After The Philosopher's Stone
1. Nymphadora Tonks
Tonks is the perfect example of what happens when a character from the books is thrown into the film but is given hardly any context or screen time to develop their character, but the filmmakers assume the audience have read the books to have a rough idea of what's going on.
Tonks is a metamorphmagus which means she can change her appearance at will. This is shown during a comedic scene in the films, but later on during the Half-Blood Prince, when Tonks' role was significant in the books, the films cut her right down.
Throughout the sixth novel, Tonks is severely depressed and spends a lot of time struggling with her mental health. While there are clues strewn throughout, it becomes clear at the end, that Tonks is in love with Remus Lupin, who rejects her. Even when the two admit their love for each other, their relationship is rocky over the remainder of the story. Remus even comes close to abandoning her and their unborn child, and then both are killed in the Battle of Hogwarts. The film doesn't explain that Tonks is related to Bellatrix Lestrange who is her aunt... and the very person who murders her!
Instead we just see Tonks appear in a scene that wasn't in the books (the Death Eater attack on The Burrow) and she announces that she and Lupin are married. It was very jarring and wrecked the story of one of the most popular couples in the franchise.