Stealther is the boss of zones J and K from Darius Force. It is shaped after a chameleon.
Stealther will be constantly walking back and forth during the fight, often stopping to attack. His attacks include a three-way shot from his horn, land mines and sticking his tongue. If you get hit by the tongue the ship will get temporarily trapped in place. After a while he will turn transparent, becoming invulnerable, then begin shooting missiles from his back and lasers upwards.