The Ridley Robot (or Mecha Ridley) is a robot modeled after Samus Aran's arch-enemy Ridley, and the final boss of Metroid: Zero Mission. The robot is incomplete, as it lacks walking and flying units, but has numerous cables coming out of it, which are most likely connected to an unseen interface, possibly for power and computer control. Thus, it can only move by crawling. However, it makes up for it with plenty of firepower and other offensive capabilities. It is first seen when Samus first enters the Space Pirate Mother Ship as one of its eyes opens, either activating or sensing Samus's presence.
After exploring the Space Pirate Mother Ship and the temple of Chozodia, Samus comes to a huge, dark room near the control bridge of the Mother Ship, where the Ridley Robot is kept. Upon entering, Samus is locked in, and scraping sounds are heard as the Ridley Robot crawls towards Samus, and lights up the room.
The Ridley Robot's weak point is the glowing red circle on his stomach. Samus's Beam weapons won't have any effect on the robot, so Samus must fire Missiles or Super Missiles at the glass covering to destroy it.
The robot's attacks include large fireballs from its mouth, homing missiles from a unit on its back, lasers from its eye, and claw swipes. In addition, the robot will also move its head so Samus's attacks will be blocked by its neck.
The battle will be harder and longer if Samus collects all the hidden items before facing the Ridley Robot. Once defeated, the Ridley Robot shuts down, but then triggers the Mother Ship's self-destruct mechanism, leaving Samus 3 (on Hard mode), 5 (on Normal mode), or 7 (on Easy mode) minutes to escape.