Grey Matter

Grey Matter is the Omnitrix's DNA sample of a Galvan from the planet Galvan Prime.

Ben as Grey Matter
Grey Matter is a grey skinned, frog-like, bipedal alien that is only four inches tall with large green eyes, which have rectangular pupils. He wears a white jumpsuit with a black stripe going down it.

In the original series, Grey Matter wore the Omnitrix symbol on his back and his eyes were yellowish-green. He spoke with a high-pitched voice.

In Ultimate Alien, Grey Matter wore the Ultimatrix symbol on his chest.

In Omniverse, 11 year old Grey Matter looks exactly the same as the original, but his collar is now black. His skin tone is also slightly different.

16 year old Grey Matter now has a green jumpsuit with a black belt. His suit collar is now black, and the stripe on his head and jump suit are no longer present. He wears black, fingerless gloves with a green rectangle on the back. His neck is slightly longer. His Omnitrix symbol continues to be present on his back, and his voice is slightly deeper.

Gwen as Grey Matter
Gwen as Grey Matter has Gwen's hair and more oval shaped eyes, with much smaller pupils. She wears a light blue jump suit with dark blue sleeves. She wears the Omnitrix symbol on her back. She also lacks the stripes Ben's form has.

Powers and Abilities
Grey Matter's small size belies his great calculative and technical intellect. He can create complicated machines from spare parts, understand the function of any device at a glance, and make sophisticated repairs to complex machines, (such as a warp-drive engine). Grey Matter's intellect serves as a problem solver and analytical help in difficult situations. This allows Grey Matter to think more strategically when brute force is inefficient.

Grey Matter can sometimes manipulate living things by stimulating certain parts of their nervous system, if such beings can be controlled by external stimuli.

Grey Matter's size allows him to squeeze into small spaces and can climb walls due to tiny suction cups on his skin. He also has sharp teeth and his slimy skin makes him difficult to grab.

Grey Matter appears to be stronger than he looks, as he was strong enough to move a cleaner's bucket with mops in it in Ultimate Weapon, and in So Long, and Thanks for All the Smoothies, he was able to break a coolant pipe to freeze the Vreedle Brothers.

According to Derrick J. Wyatt, Grey Matter is amphibious and has gills.

Grey Matter has a long prehensile tongue, owing to his insectivore nature. As a Galvan, he also possesses a 'pre-brain' which deals with all basic bodily functions.

Grey Matter was able to understand Pyxi's speech in Rad.

Weaknesses
Grey Matter's small size makes him unsuitable for physical battle, so he must outsmart his enemies in a fight. Animals like dogs and cats can be a problem, as they may see Grey Matter as a chew toy or food to them.

Ben

 * Grey Matter first appeared in Washington B.C.. Grey Matter searched through in cereal boxes for a Golden Sumo Slammer card.
 * In Hunted, Grey Matter defeated Kraab and Sixsix.
 * In A Small Problem, the Omnitrix malfunctioned, trapping Ben as Grey Matter for most of the episode.
 * In Secrets, Grey Matter defeated one of Vilgax's drones.
 * In Truth, Grey Matter defeated a Null Guardian.
 * In Grudge Match, Grey Matter defeated one of Slix Vigma's drones.
 * In Ultimate Weapon, Grey Matter snuck into a building, let Gwen and Max come in and opened a safe.
 * In They Lurk Below, Grey Matter saved a drowning man.
 * In Ghostfreaked Out, Grey Matter escaped Zs'Skayr.
 * Grey Matter appearaed six times in Back With a Vengeance. Fistly, he appeared when Ben unlocked the Master Control. Then, he appeared in a photo. Grey Matter later tried to escape from Vilgax and Kevin. In the Null Void, Grey Matter escaped Kevin on a Null Guardian, then tried to escape a Null Guardian. At the end of the episode, Ben accidentally transformed into Grey Matter, realizing that the Master Control is once again locked.
 * In Midnight Madness, Grey Matter was hypnotized into being Gwen's slave.
 * In Merry Christmas, Grey Matter accidentally destroyed the Rustbucket's air conditioner and later destroyed the Jinglelator.
 * In The Unnaturals, Grey Matter stopped some thieves from stealing the Liberty Bell and won an MP3 player in a contest.
 * In Be Afraid of the Dark, Grey Matter escaped Zs'Skayr and built a Sun Gun.
 * In Perfect Day, In a dream, Grey Matter defeated a mutated Cash and J.T..
 * In Secret of The Omnitrix, Grey Matter defeated Dr. Animo.
 * In Ben 10: Destroy All Aliens, Grey Matter escaped from Retaliator.

Gwen 10

 * In Gwen 10, Grey Matter was chased by a raccoon.

Ben 10 Shorts

 * In Snack Break, Grey Matter failed to retrieve his snack in a vending machine.

Ben

 * In Ben 10,000 Returns, Grey Matter was re-unlocked by Ben 10,000.

Albedo

 * In Double or Nothing, it is revealed Albedo can only be Negative Grey Matter for about a second before reverting back.

Ben

 * In Have I Got a Deal for You, Grey Matter was part of an accidental transformation chain along with Jury Rigg and Nanomech.
 * In So Long, and Thanks for All the Smoothies, Grey Matter stopped the Vreedle Brothers from shooting at them.
 * In Of Predators and Prey: Part 2, Grey Matter defeated Tyrannopede.
 * In Rad, Grey Matter repaired Rad's ship for them to escape.
 * In It's a Mad, Mad, Mad Ben World: Part 2, Grey Matter repaired Brainfrog's Omnitrix who repaired his.
 * In A New Dawn, Grey Matter appeared for a short time when Ben was cycling through his aliens.

No Watch Ben

 * In And Then There Was Ben, Grey Matter was used to disable the shields on the Chimerian Hammer.

Ben 10

 * Washington B.C. (first appearance)
 * Hunted
 * A Small Problem (accidental transformation, selected alien was Ripjaws)
 * Secrets
 * Truth (accidental transformation, selected alien was Four Arms)
 * Grudge Match
 * Ultimate Weapon
 * They Lurk Below (accidental transformation, selected alien was Ripjaws)
 * Ghostfreaked Out
 * Back With a Vengeance (8x; last time was an accidental transformation, selected alien was Four Arms)
 * Midnight Madness (under hypnosis)
 * Merry Christmas (2x; second time was an accidental transformation, selected alien was Four Arms)
 * The Unnaturals (accidental transformation, selected alien was XLR8)
 * Be Afraid of the Dark (accidental transformation)
 * Perfect Day (accidental transformation, selected alien was Heatblast)
 * Ben 10: Secret of the Omnitrix (accidental transformation, selected alien was Stinkfly)
 * Ben 10: Destroy All Aliens

Ben 10 Shorts

 * Snack Break

Ben 10: Ultimate Alien

 * Double or Nothing (x3; first re-appearance; used by Albedo)

Ben

 * Have I Got a Deal for You (first re-appearance; accidental transformation; cameo)
 * So Long, and Thanks for All the Smoothies (accidental transformation, intended alien was Rath)
 * Of Predators and Prey: Part 2 (accidental transformation, intended alien was Way Big)
 * Rad
 * It's a Mad, Mad, Mad Ben World: Part 2
 * A New Dawn (cameo)

No Watch Ben

 * And Then There Was Ben

Ben 10

 * 4' Grey Matter
 * Metamorfigure Grey Matter (Binoculars)

Ben 10: Alien Force

 * Alien Creation Figures from (Ben 10) Diamondhead and Grey Matter

Ben 10: Ultimate Alien

 * Alter Aliens Ben to Grey Matter and Goop to Way Big

Etymology
Grey Matter is named after grey matter, one of the components of the central nervous system.

Trivia

 * According to Derrick J. Wyatt, Grey Matter is Ben's smartest alien.
 * As shown in Ken 10, Grey Matter is smart enough to unlock the Prototype Omnitrix's Master Control.
 * It was revealed that neither Azmuth nor Albedo was the source of Grey Matter's DNA sample.
 * A running gag in the original series was that when Ben selected an alien with enhanced strength, he got Grey Matter instead.