|[List of appearances]|
Dudley is fat, spoiled, and constantly rude to Harry but becomes more fearful of him after Rubeus Hagrid gives him a pig's tail. In the book, (but not in the movie) Fred Weasley gives him a Ton-Tounge Toffee that makes his tongue grow.
In Harry Potter and the Philosopher's Stone, Dudley, Harry, Dudley's friend, Petunia Dursley and Vernon Dursley go to the zoo for Dudley's birthday. Dudley falls in the snake cage after Harry speaks parseltongue.
In Harry Potter and the Order of the Phoenix, Dudley and Harry get attacked by two Dementors and Dudley almost lost his soul. Harry saved him, and Dudley became more respectful of Harry, and when Harry was relocated, Dudley properly thanked Harry for saving his life.
Harry Threatning Dudley in LEGO Harry Potter: Years 5-7