Cyrax is the leader of all the aliens. Before Presto's egg hatches, he appears in front of the egg. In order to get the Presto egg, you have to defeat Cyrax. He can summon Mini-Sylvesters, miniature versions of Sylvester, and all aliens you've encountered in Adventure Mode.
Cyrax has 6 blue tentacles, a green body, 5 black circles around his head, which may be his eyes, and a giant brain-like head.
After losing the legendary Battle of Tank 5, Cyrax moved on and eventually became host of his own late night variety show. Some people call it a cerebral high-brow interview program, while critics have deemed it a lowest-common-denominator sleaze-fest. There is certainly no end of controversy to his show, and Cyrax wouldn't have it any other way.
- Cyrax is the last alien you face (8th), so he is considered the toughest one.
- During the fight with Cyrax, Gus can actually be harmed by lasers, this is very strange despite the game saying that he is immune to lasers. This may be because there is no food to feed Gus with in Tank 5.
- He is the only alien in Sandbox Mode that you cannot put in your tank.
- The name "Cyrax" may be a homage to and pun on Korax, the final boss from the First-Person Shooter Hexen. "Corax" is Latin for "raven", and ultimately comes from the Greek κοραξ (korax).
- Cyrax is the second alien to laugh, after Gus.
- Cyrax is the only alien with visible organs. Visible brains are a common cliche in sci-fi movies dealing with alien invasions (such as the comedy Mars Attacks!)
- His cephalopod appearance might be a reference to the Martians in Herbert Wells' classic War of the Worlds.
- Unlike most characters, Cyrax's story, instead of a sprite of himself, has a scene called Talkshow, which includes Cyrax behind a desk labled "Food 4 Thought with Cyrax", along with Gus on a stage with a microphone.