They made up the music by them selves
classical
It is called "Harry Potter Prologue"
composes music for lots of films e.g E.T, Harry Potter (series 1-3), Jaws and MANY MANY more!!!!!!
The Harry Potter theme (along with all the other songs from the films) were composed by John Williams, who is also famous for writing the musical scores for the Star Wars films.
Harry Potter and the Half-Blood Prince.
John Williams wrote the score for the Star Wars movies. He also scored the music for various other films, like Harry Potter.
The "Beethoven" series of films, for one.
He is a composer ( he has composed for the movies Indiana Jones, Jurassic Park, Harry Potter, E.T. and many more) so most likely his compositions are classical
For Harry Potter and the Sorcerer's Stone, Harry Potter and the Chamber of Secrets, and Harry Potter and the Prisoner of Azkaban: John Williams For Harry Potter and the Goblet of FIre: Patrick Doyle For Harry Potter and the Order of the Pheonix and Harry Potter and the Half Blood Prince: Nicholas Hooper For Harry Potter and the Deathly Hallows, Part 1 and Harry Potter and the Deathly Hallows, Part 2: Alexandre Desplat
No, the music for Harry Potter has been composed in recent years for the movies.
The first Harry Potter movie to be nominated for an Academy Award (Oscar) was Harry Potter and the Sorcerer's Stone (the first Harry Potter movie). It was nominated for three Academy AwardsBest Art Direction-Set Decoration, Stuart Craig (art director), Stephanie McMillan (set decorator)Best Costume Design, Judianna MakovskyBest Music, Original Score, John Williams
The score was composed by John Williams. The conductor was William Ross, and the orchestrator was Conrad Pope.