The Beast Warriors are the primary monsters deployed by the Reconstructive Experiment Empire Mess. Created through genetic reconstruction, they are hybrids made from Earth and alien genes, each designed as a specialized weapon against the Flashmen.

Deus Beast Warriors are stronger creations infused with the genes of Great Emperor Lar Deus himself, making them more dangerous than the standard Beast Warriors.

When defeated at human size, many monsters are enlarged by Kraagen, forcing the Flashmen to battle them with Flash King, Titanboy, or Great Titan.