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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 also has the upper head stripe of Four Arms, and his lower jaws is the same structure as a Tetramand. Unlike Grey Matter or Four Arms, Grey Arms has wrinkles on his upper lip.

Grey Arms wears the Omnitrix symbol on his chest.

Powers and Abilities

Grey Arms, being half Tetramand/half Galvan, has enhanced strength, albeit not as strong as a Tetramand due to the asymmetric body of the fusion and not being pure. He also has shown higher intelligence, presumably coming from his Galvan half.


Due to his asymmetric body and having one functionally strong arm, he can't use his enhanced strength. In addition, he suffers from imbalance issues.


Ben 10


Ben 10

Season 1

Naming and Translations

Language Name Origin
Italian Materia Grigiax2 Translation of English name
Portuguese (Br) Braços Cinzentos Translation of English name
Russian Силаноид Translation of English name
Spanish (HA) Brazos Grises Translation of English name


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


Introduced in Season 1 CannonboltDiamondheadFour ArmsGaxGrey MatterHeatblastOverflowStinkflyUpgradeWildvineXLR8
Introduced in Season 2 RathShock Rock
Introduced in Season 3 HumungousaurSlapback
Introduced in Season 4 GoopJetrayWay Big
Introduced in Season 5 Big ChillBloxxBuzzshockChromastoneRipjawsSpidermonkeySurge
Omni-Enhanced Aliens CannonboltDiamondheadFour ArmsGrey MatterHeatblastOverflowStinkflyWildvineXLR8
Omni-Kix Aliens CannonboltDiamondheadFour ArmsHeatblastHumungousaurJetrayRathShock RockSlapbackXLR8
Omni-Naut Aliens HeatblastJetrayHumungousaurShock Rock
Fusion Aliens Amalgam AlienAmalgam BenGrey ArmsXLRArmBlastDiamondHeat
Non-Canon Aliens Banana AlienBlack Hat AlienHotdawgMole-StacheScooter Alien
Non-Canon Fusion Aliens Omnitrix Glitch FusionDiamondhead-Humungousaur FusionRath ArmsShock Blast