In the Harry Potter movies, Dumbledore dies in the sixth movie, "Harry Potter and the Half-Blood Prince." While trying to retrieve a Horcrux (an object containing a fragment of Voldemort's soul) from a cave, Dumbledore drinks a powerful poison meant for Harry.
As they return to Hogwarts, Draco Malfoy, under the influence of Voldemort, disarms Dumbledore at the top of the Astronomy Tower. Snape, who had secretly been loyal to Dumbledore all along, arrives and kills Dumbledore at his own request to prevent Draco from doing so and ensure Voldemort remains unaware of Snape's true allegiance. Dumbledore's death deeply affects Harry and becomes a pivotal moment in his journey to defeat Voldemort.