Detective Pikachu is the titular deuteragonist of the video game with the same name and it's live-action film adaptation.
In the titular video game, he is voiced by Tōru Ōkawa in the Japanese dub and Kaiji Tang in the English dub. In the movie, when he is speaking "normally", he is voiced by Ryan Reynolds, who is better known for portraying Theo/Turbo from Turbo, Guy from the Croods, the anti-hero Deadpool from the movie of the same name and played Green Lantern from the DC film with the same name. Reynolds also provides Pikachu's facial motion captured. When he is speaking in "Pokemon Speak", he is voiced by Ikue Otani.