Ridley Robot, also known as Mecha Ridley, is an unfinished robot build by Ridley, made to look identical to its creator. Mecha Ridley is the final boss of Metroid: Zero Mission.
At the end of her long quest through the Chozodia temple and the Space Pirate Mothership, Samus eventually stumbles upon a supposedly deactivated Mecha Ridley. However, suddenly, all exits to the room are locked and Mecha Ridley springs to life, triggering a conflict between the two and the final boss battle of the game. Through the heavy weaponry of missiles and super missiles, Samus eventually defeats and destroys Mecha Ridley. However, as a last resort, the machine tries to take Samus with it by setting a self-destruction timer for the Mothership, but Samus flees just in time.
- Mecha Ridley's health and strength depends on the player's percentage of collecting the hidden items prior to the fight. If Samus fights Mecha Ridley with every hidden item located in the game, Mecha Ridley's offensive and defensive power triples, making the battle longer and more dangerous.