TMDb/Dune: Part Three TV The ultimate box office showdown: Dune: Part Three vs. Avengers: Doomsday on December 18, 2026. Who will win "Dunesday"? May 4, 2026 AceShowbiz - The highly anticipated cinematic event of December 18, 2026, will witness the simultaneous worldwide release of two blockbuster films: Dune: Part Three and Avengers: Doomsday. This unprecedented clash, dubbed "Dunesday," is set to captivate audiences globally as both franchises vie for box office supremacy during the holiday season. Already, Dune: Part Three has secured a significant advantage in the IMAX arena.