The Persona 4 protagonist is one of the few in the series to have a canon name across all media. Not all of them have one, as is the case for the hero of Persona 1 and even Joker, which is just a pseudonym. That name is Yu Narukami. However, the player does not have to use this name in Persona 4 and Golden if they do not want to. They can choose their own unique name for the lead hero. If you play something like Persona 4 Arena or another spin-off or watch the anime adaptation, Yu Narukami will be used for the protagonist.