What is the name of the first Pokémon film in English?

The first Pokémon film in English is Pokémon: The First Movie – Mewtwo Strikes Back.

The film is based on the original Pokémon anime and centers on Mewtwo, a genetically engineered Pokémon who challenges the meaning of identity, creation, and strength. Ash, Misty, and Brock are invited to a mysterious island, where they discover that the invitation conceals Mewtwo's plan.

The Japanese film premiered on July 18, 1998, under the title Pocket Monsters the Movie: Mewtwo Strikes Back. The English-language version was released in North America on November 12, 1999, by Warner Bros. It was accompanied by the short Pikachu's Vacation in theatrical presentations.

The 2019 computer-animated remake is called Pokémon: Mewtwo Strikes Back – Evolution. That title is not the name of the original film. The original is also sometimes shortened in conversation to “Mewtwo Strikes Back,” but its full English release title identifies it as the first Pokémon movie.