- "A construction Chimera designed to destroy the old Chimera Lab to make way for a new building."
- — Battle Memory
The Steel Mechorilla is a boss in Mother 3, found at the top of Snowcap Mountain in Chapter 7. It resembles a gorilla whose hands were replaced by two steel balls and its ears replaced with satellites. According to Boney, it is a mechanical chimera.
After the Masked Man pulls Lydia's Needle, he flies off and releases the Steel Mechorilla to attack Lucas and his group. In battle, the monster is weak against PK Flash and PK Thunder; however, using PK Thunder more than twice will cause it to short-circuit and go berserk, attacking all party members every turn for a higher amount of damage than before.
There is a sprite of the Steel Mechorilla facing north, although this is not used in-game. This might have been a back sprite.
Oddly enough, although Lucas only fights it because it attacked him, if he loses the fight he still has to go back and defeat it, rather than simply searching for the next needle.
His battle sound is Battle Sound 60, a battle sound used only by large bosses, which falls under Code Numbers 939 for regular attack, 940 for Smaaaash! and 941 for Miss.