Professor Oak is the Pokémon professor who gives the player a starter Pokémon in the original games.
His laboratory is in Pallet Town, where the player receives a choice among Bulbasaur, Charmander, and Squirtle in Pokémon Red, Green, and Blue. The rival also chooses one of the remaining Pokémon, establishing the game’s first major relationship.
Oak’s research focuses on Pokémon and their relationship with people. He gives the player a Pokédex and asks them to document the species encountered during the journey. In the anime, his role is expanded through his relationship with Ash and other Trainers.
Later Pokémon games introduced new professors, including Elm in Johto, Birch in Hoenn, and Rowan in Sinnoh. Those names belong to different regions, not the original Kanto adventure.