Kingpin

The Kingpin is an alien enemy cut from Half-Life. It never went further than the concept stage and was therefore never scripted, due to a lack of convincing AI and gameplay goals.

Depiction

 * Its massive brain fills its entire body.
 * Psionic attack and psionic defense, making it immune to missile weapons.
 * Four eyestalks, giving it a 360° vision.
 * It was do make clicking sound when walking on its three chitinous legs.