Berserker is an enemy in Kingdom Hearts II and first appears in Twilight Town when Sora attempts to meet Kairi.
Berserkers are very bulky and wield giant claymore-like weapons, like Saïx's, used to attack and defend. They are the biggest lesser nobodies and are very powerful. They are controlled by Saïx, with who they wear a resemblance in various ways.
Anatomy
Berserkers are giant Nobodies. They seem to wear heavy armor that cover they're body, unlike other nobodies, they don't have silver on them, but instead have bronze-like coloring. They're arms and legs are small at first, but the hands and feet are gigantic. Due to their armor, the only parts that can be seen of their "skin" are the hands and part of the neck/face, which are ink-black. When using a special attack(which is like the "Berserk" Reaction Command) they become of small size, hanging from their claymore-like weapons with their small hands.
Strategy
Berserkers are very strong and have an equally strong defense. Moving in for a head on attack can be risky. A good way to deal with them is to come in close an reflect his attacks waiting for his Reaction command to show up. Using it will greatly diminish the Berserkers health as well as any other Nobodies that you capture with it. A good alternative is using thunder or blizzard at a distance to help preserve HP or using magnet followed by a limit or Thunder to finish the Job.