Slench

Slench is a boss Samus must fight at the end of four levels on Metroid Prime: Hunters. He resembles a giant robot eyeball. He consists of two forms, A and B. He is invincible during his first form, and is attached to a wall (or ceiling, in Slench 4's case) by three tentacles that power the energy blasters used to attack Samus. He resided in Biodefense Chamber B.

Apperances

 * His first appearance is in Alinos, on your first visit.
 * His next appearance is in Arcterra, again, on your first visit.
 * You fight him again on your return to the Celestial Archives.
 * His final appearance is in your second visit to Vesper Defense Outpost.

Slench 1
Slench 1 is his first appearance, where his tentacles that attach him to the wall are vulnerable to any weapon. When you destroy all three tentacles, he detaches from the wall and becomes vulnerable to attack, which is his B form.

Slench 2
Slench 2 is his second appearance, and this time his tentacles are only vulnerable to the Judicator, and he shoots torpedoes from his eyeball that you can shoot for powerups. In his B form, he is most vulnerable to the Judicator.

Slench 3
Slench 3 is his third appearance, and possibly the most difficult to destroy. His tentacles are only vulnerable to the Battlehammer. In his B form, he has a powerful new attack where he begins to shake and then rams you, dealing a lot of damage. However, this can be narrowly avoided by going into Morph Ball mode, and boosting out of the way.

Slench 4
Slench 4 is his final form. He is arguably the easiest to defeat, due to him moving up to the ceiling. His energy blasters shoot Judicator shots, which can freeze you. His tentacles are only affected by the Magmaul this time, and his B form first has him falling to the floor and rolling, dealing heavy damage if hit. This part of the B form can be avoided by standing against the door. When he finally goes up into the air and floats like normal, he  inherits the ram attack from Slench 3. His center is most vulnerable to the Magmaul.