Grey Matter

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

Appearance
Grey Matter is a grey-skinned, frog-like, bipedal alien, only four inches tall with large green eyes with little minus sign like 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.

Gwen as Grey Matter has Gwen's hair and has 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 Grey Matter has.

In Ultimate Alien, he wears 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 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 as well as on his jump suit are no longer present. He wears black, fingerless gloves with a green rectangle. His neck is slightly longer. His Omnitrix symbol continues to be present on his back, and his voice is slightly deeper.

Powers and Abilities
Grey Matter's size belies his great calculative and technical intellect. He can create almost anything from spare parts and know the function of any device at a glance. Grey Matter's intellect serves as a problem solver and analytical help in difficult situations.

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

Grey Matter's size allows him to squeeze into small spaces and he can climb walls thanks 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 pipe to freeze the Vreedle Brothers.

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

Grey Matter has a long prehensile tongue owing to his insectivore nature.

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 toy or food to them.

Original Series

 * Grey Matter first appeared in Washington B.C..
 * ​Grey Matter was searching in cereal boxes for a Gold 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.
 * In Back With a Vengeance:
 * ​Grey Matter appeared 8 times.
 * 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 Jingleator.
 * In The Unnaturals:
 * ​Grey Matter appeared.
 * In Be Afraid of the Dark:
 * ​Grey Matter escaped Zs'Skayr and built a sungun.
 * In Perfect Day:
 * In a dream, Grey Matter defeated a mutated Cash and JT.
 * In Ken 10:
 * ​An alternate timeline Grey Matter was used by Kenny to escape his room.
 * Later, the alternate timeline's Grey Matter unlocked his Omnitrix's Master Control.
 * In Ben 10: Secret of The Omnitrix:
 * ​Grey Matter defeated Dr. Animo.
 * In Ben 10: Race Against Time:
 * ​An alternate timeline Grey Matter caused trouble in a diner.
 * In Ben 10: Destroy All Aliens:
 * ​Grey Matter escaped from Retaliator.
 * In Snack Break:
 * ​Grey Matter failed to retrieve his snack in a vending machine.

Ultimate Alien

 * In Ben 10,000 Returns:
 * Grey Matter was re-unlocked by Ben 10,000.
 * In Double or Nothing:
 * Negative Grey Matter explains that he won't attack Ben, Gwen or Kevin anymore. Until it is revealed Albedo can only be Negative Grey Matter for about a second before reverting back.

By 16 year old Ben

 * In Have I Got a Deal for You:
 * ​Grey Matter of three straight accidental transformations with Ben turning into his three smallest aliens (Jury Rigg, then Grey Matter, then 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.

Appearances
{{Scroll box
 * content====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) (last time was an accidental transformation; selected alien was Four Arms)
 * Game Over (Cameo)
 * The Unnaturals (accidental transformation; selected alien was XLR8)
 * Be Afraid of the Dark (accidental transformation)
 * Perfect Day (accidental transformation; selected alien was Heatblast)
 * Ken 10 (used by Kenny Tennyson) (alternate timeline)
 * Ben 10: Secret of The Omnitrix (accidental transformation; selected alien was Stinkfly)

Ben 10 Shorts

 * Snack Break

Ben 10: Ultimate Alien

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

Ben 10: Omniverse

 * 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

Movies

 * Ben 10: Race Against Time (accidental transformation; selected alien was Four Arms) (Race Against Time Timeline version)
 * Ben 10: Destroy All Aliens}}

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

Trivia

 * 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 is that when Ben selects an alien with enhanced strength, he gets Grey Matter instead, makig his chang into Grey Matter more ironic.
 * Grey Matter is Ben's smartest alien.