In the Pokémon TV series, Dr. Fuji is the scientist who created Mewtwo.
Dr. Fuji conducts genetic research using DNA from the Mythical Pokémon Mew. The experiments take place on New Island and produce Mewtwo, an artificially created Pokémon with extraordinary psychic power. The project is funded and controlled by Giovanni, the leader of Team Rocket.
In the original television continuity, Dr. Fuji’s work and Mewtwo’s creation are connected to the destruction of the laboratory on New Island. The story establishes Mewtwo’s anger toward humans and its struggle with identity. Professor Oak is a Pokémon researcher, but he did not create Mewtwo. Some later adaptations use the name Dr. Fuji differently, so the character’s exact role can vary by continuity.