Bombermen are robot-like people with flat computer screen faces that have eyes, but no visible mouth, within a squared or circular helmet. They possess a roundish body, long limbs and usually balled hands and feet.
At the beginning of the Bomberman series, the Bombermen people were working in a underground bomb factory in Planet Bomber. There was a challenge to determine the best Bomberman in the bomb factory by fighting other Bombermen. Long after, a Bomberman got tired of this boring life and escaped the factory, making the Bombermen species become free and more humanoid (and changed their appearance accordingly).
Other than the Bombermen on Planet Bomber, there are Bombermen with alien origins. Some of those Bombermen are human turned to cyborgs, like Max. Some of the foreign Bombermen are intelligent robots created by good or evil people. Others are just Bombermen born from different planets.