One sick dude from space.
"Omega Pirate, most powerful of the Elite Pirate Forces. Omega Pirate can become invisible to normal sight. It is vulnerable when cloaked, as all energy is drawn from defense systems. By exposing itself to Phazon, it can regenerate damaged tissue and organs. Considered the pinnacle of the Elite Pirate program, this enemy should be handled with extreme caution and maximum firepower." - Log Book Excerpt from Metroid Prime