Grey Arms is a fusion of Four Arms' DNA and Grey Matter's DNA. He cannot be accessed unless the Omnitrix is tampered with.


Grey Arms has the body of Four Arms, but the head of Grey Matter (although much larger). He has three eyes, two of which are those of Four Arms and one is a large Grey Matter's eye. He has one arm of Four Arms on his right side and 3 arms of Grey Matter on his left side. His right leg is Grey Matter's and left is Four Arms'. Grey Arms wears the Omnitrix symbol on his chest.

Powers and Abilities

He is shown to still have the same intelligence as greymatter

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He is not strong and durable like Four Arms. He has only 1 arm that can help him when strength is required.


Ben 10


Ben 10


His name is the combination of Grey Matter and Four Arms.


  • Grey Arms is the first fusion alien in the reboot.
Ben 10 Reboot Aliens
Introduced in Ben 10
CannonboltDiamondheadFour ArmsGaxGrey MatterHeatblastHumungousaurOverflowRathShock RockSlapbackStinkflyUpgradeWildvineXLR8Jetray
Omni-Enhanced Aliens
CannonboltDiamondheadFour ArmsGrey MatterHeatblastOverflowStinkflyWildvineXLR8
Fusion Aliens Non-Canon
Amalgam BenGrey ArmsXLRArmBlastDiamondHeat Hot Dog AlienGlitch Fusion
Omni-Kix JetrayOmni-Kix SlapbackOmni-Kix ClockworkOmni-Kix NRGOmni-Kix HeatblastOmni-Kix Four Arms
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