The Cold Heroes are a collection of the strongest personnel of multiple eras. It was them who defeated Queen E-33 55 years ago, as mentioned by Dry Leonhard and Milo. They are preserved by cryopreservation and are only awakened during extreme times of need.
Their members consist of Sophie Vista (a.k.a. Ice Witch), Sion, the Original Chimera, Dike, Diorasis IV and his sister, Kasim, Ralph Paulo and Electric Eel. Each member is extremely strong to the point of just two of them being strong enough to destroy a Blue Flower.