Which arch-villain is finally destroyed at the end of "The Deathly Hallows"?

The arch-villain finally destroyed at the end of Harry Potter and the Deathly Hallows is Lord Voldemort. His defeat ends the Second Wizarding War and the central conflict of the Harry Potter series.

Voldemort is defeated during the Battle of Hogwarts, after Harry returns from the Forbidden Forest and confronts him in the Great Hall. The outcome depends on the Elder Wand’s allegiance: Draco Malfoy disarmed Albus Dumbledore, Harry later defeated Draco, and the wand therefore recognized Harry as its true master. When Voldemort casts the Killing Curse, the wand refuses to kill its master and the curse rebounds on Voldemort.

The story also reveals that Voldemort’s attempt to kill Harry years earlier accidentally created a Horcrux inside Harry. Harry’s sacrifice in the forest destroys that fragment, leaving Voldemort mortal. His earlier Horcruxes must also be destroyed before he can be permanently defeated.

A common mix-up comes from the title’s wording: Deathly Hallows refers both to the final book and film and to the three legendary objects—the Elder Wand, Resurrection Stone, and Cloak of Invisibility. Voldemort seeks them, but their symbolism and ownership ultimately contribute to his downfall.