- Not to be confused with the Robot Masters.
Master Robots are the bosses that appear in the Master System/Game Gear version of Sonic the Hedgehog 2 and Sonic Chaos. They are an elite robot series designed by Dr. Ivo Robotnik. Built for the sole purpose of collecting the Chaos Emeralds and stopping Sonic the Hedgehog and Miles "Tails" Prower from ruining Dr. Robotnik's plans, each of the Master Robots patrolled a zone on South Island until their destruction at the hands of the heroes.
Members in Sonic the Hedgehog 2
The Antlion Mecha is the Master Robot of Under Ground Zone. It is a robotic antlion larva with giant mandibles. Dr. Robotnik dropped Sonic to confront it, but ended up accidentally destroying his own creation.
|Mecha Sea Lion||
The Mecha Sea Lion is the Master Robot of Aqua Lake Zone. It appears to be based on a sea lion at the circus or zoo, as it skillfully used a red ball in battle.
The Mecha Pig is the Master Robot of Green Hills Zone. It is a pig taking the appearance of sumo wrestler, and attacks by rolling into a lethal ball that strikes the other side of the hill.
The Pig-Boar Mecha is the Master Robot of Gimmick Mountain Zone. It is based on a wild pig or boar, and attacks by charging straight ahead until it hits Sonic or the side of the screen, causing debris and retracting its spikes.
|Crystal Egg Zone boss||
Members in Sonic Chaos
|Lady Bug Boss||
|Bead Worm Boss||
The Bead Worm Boss is the Master Robot of Gigalopolis Zone. It is composed of numerous dangerous balls that it flicks to attack.
|Bouncy Boss Robot||
|Tree Crawler Boss||
The Tree Crawler Boss is the Master Robot of Mecha Green Hill Zone. It crawls along a single palm tree while firing bullets at its foe.
- Most of the original Master Robots are based or have possibly inspired enemy Badniks from other Sonic the Hedgehog video games:
- Antlion Mecha–Antlion from Sonic the Hedgehog CD and Antlion from Sonic Lost World
- Goose Mecha–Balkiry from Sonic the Hedgehog 2 (Sega Genesis version)
- Mecha Sea Lion–Steelion from Sonic the Hedgehog 4: Episode II
- Mecha Pig–Buton from Sonic the Hedgehog 2 (8-bit)
- Pig-Boar Mecha–Fullboar from Sonic the Hedgehog 4: Episode II
- Lady Bug Boss–Boing-o-Bot from Sonic Chaos
- The Master Robots are simply called "bosses" in the Japanese manuals, and do not have a group name to distinguish them. This may be analogous to how Badniks in general gained their name in English.
- There is confusion over what exactly constitutes a Master Robot, as the scoring heading for both manuals has a separate entry for Silver Sonic and Dr. Robotnik's machines, and the latter one splits them between "Boss Robot (Zones 1–2)" and "Boss Robot (Zones 3–5)"; however, the text clearly states every boss in the zones' third Acts are included.
- Sonic the Hedgehog Triple Trouble contains a similar group of enemies, but are instead labeled Boss Robots in English localization.
- Sonic the Hedgehog 2 (Master System) European instruction booklet, pg. 24. "At the end of the third Act of each Zone, you'll meet with one of Robotnik's Master Robots."
- Sonic Chaos (Master System) AU instruction manual. "At the end of the third Act of each Zone, you'll meet with one of Robotnik's Master Robots."
- Sonic the Hedgehog Triple Trouble (Game Gear) United States instruction booklet, pg. 7. "At the end of the third Act, you’ll face one of Robotnik’s Boss Robots."