Motormaster is a Decepticon and the Commander of the Stunticons, often referred to as "chief" by them. He combines into Menasor with Slashmark, Dragstrip, Wildbreak, and Heatseeker. His alternate mode is an eighteen-wheeler truck and he regularly boasts that he is the king of the road.
Motormaster was responsible for a strange signal coming from the collapsing sewers, prompting the Decepticons to investigate just what was going on down there. After watching them trash the sewer system, he decided that they were his kind of robots... but there was going to be a rumble anyway! Motormaster put up a pretty good fight, but after the Decepticons bested him in battle he offered his services as a terrorist to their cause.
In King of the Hill (Part 2), after Heatseeker found a device which could help track Cybertronian tech, he reported back to Motormaster. Though not exactly happy with the failure of Heatseeker's assigned mission, Motormaster accepted the device, ominously plotting to stock up on tech to help the Stunticons control the roads of Earth.
In Bee Cool, Dragstrip managed to acquire the device so that he and Wildbreak could get in Motormaster's good graces.
In The Great Divide, Dragstrip presented a Gravitic Adjuster to Motormaster that he tested on Wildbreak before Motormaster called his minion off and promptly sent him to stir up some trouble to show the Autobots and humans alike that the Stunticons meant business.
In Disordered Personalities, as Heatseeker, Dragstrip, Wildbreak, and Slashmark raced in the Crown City Grand Prix, Dragstrip thought about keeping the title of "Ruler of the Roads" to himself; Wildbreak replied that Motormaster would probably run Dragstrip over, back up, and run him over again.
In The Golden Knight, when his subordinate Stunticons were on a mission to clear the humans off of the roads of Star Visitor Estates, Motormaster unexpectedly joined them, declaring that he was dissatisfied with their performance at taking over the Earth's roads and, therefore, he would show them how things were done himself.
In Railroad Rage, while accompanying the Stunticons on a road-claiming mission, Motormaster boasted that no vehicles on Earth were faster than the Stunticons - just in time for a maglev train to pass them. Declaring that he would not abide anything being faster than him, he ordered the Stunticons to retrieve its engine. After they were thwarted by the Bee Team, he answered Dragstrip's offer of "making it up to him somehow" by declaring he had many ideas for how they could do so.
In Combine and Conquer, Motormaster and the Stunticons attempted to go after a Meteorite Deflector Dish. When the Bee Team catched up to them, Motormaster ran down the Autobots and then combined with the Stunticons to form Menasor. Menasor attempted to fight back and ended up temporarily delaying the Autobots while he made his way to the Meteorite Deflector Dish. He came under attack by automated tanks which he has no trouble of handling. However, the Bee Team had managed to form into the Ultra Bee robot and knocked Menasor down. In a short fight, Menasor seemed to have the upperhand but Ultra Bee was able to use the Meteorite Deflector Dish to send Menasor flying into the sky.
In Moon Breaker, Motormaster and the Stunticons followed the Bee Team and Optimus Prime on their way to the moon to Windblade's cache. They caused a satellite to fall to Earth's orbit which delayed Optimus and Fixit from helping. Motormaster and the Stunticons evaded the Autobots and made their way to Windblade's cache. They combined into Menasor who opened the cache to find a Plasma thermal accelerator module and equipped himself with it. He used it against the Autobots and the Stunticons separated as they headed back to their ship. They reached to the Autobot's ship and merged into Menasor again in an attempt to destroy the ship. However, Menasor didn't get the chance as Ultra Bee intervened. Ultra Bee destroyed the Plasma thermal accelerator module though Menasor continued to fight. His components tried to go against it which allowed Ultra Bee to hit Menasor so hard that he separated into the Stunticons again. Optimus and Fixit arrived to see that the Stunticons were defeated. The Stunticons were all placed in stasis pods as Optimus offered to take them back to Cybertron.
- King of the Hill (Part 2) (Debut, silhouette only)
- Bee Cool (Mentioned only)
- The Great Divide
- Disordered Personalities
- The Golden Knight
- Railroad Rage
- Combine and Conquer
- Moon Breaker
- Motormaster is playable in both the Autobot and Decepticon versions of the Transformers War for Cybertron games for the DS. He can be used only for Multiplayer, Bonus Missions and Arena Mode in the Autobot version, and Multiplayer, Arena Mode and Campaign in the Decepticon version.
- In the game credits, Motormaster's name is capitalized as "MotorMaster" for reasons unknown.