Pikachu is a Pokémon. It is known for being the mascot of the series, and is a Mouse Pokémon.
In the Anime[]
Pikachu's trainer is Ash Ketchum. In the first episode of the Pokémon anime, Ash woke up late the day he was supposed to go to Professor Oak's Laboratory to obtain his first Pokémon. When he arrived at the lab, the three available starter Pokémon Bulbasaur, Charmander, and Squirtle had already been taken by other Trainers who arrived earlier. Seeing that Ash was disappointed, Professor Oak gave him Pikachu, who, at first, did not care at all for its new trainer, constantly zapping him and anyone else nearby. It refused to go into its Poké Ball, and when Ash failed to catch a Pidgey, it laughed at him. However, by the end of the episode, Ash gained Pikachu's trust by protecting it from an attack by a flock of Spearow. After defeating the flock, Ash caught a glimpse of an unknown Pokémon flying by. Ash then rushed to the next town in order to get Pikachu hospitalized quickly, as it had received multiple wounds in the fight. After Pikachu was healed, Pikachu and Ash soon became inseparable, and have always traveled together ever since.