Alien X

Alien X is a Celestialsapien ("celestial" referring to a supernatural being and "sapien" meaning "wise" in Latin) from the planet Zvezda (meaning "star" in some slavic languages, or "knowledge" from veda in Sanskrit).[40] Alien X is capable of warping reality at a whim. He has a black body covered with tiny white stars, white hands, black feet, green eyes, and three horns protruding from his head. Alien X possesses three distinct personalities: Serena (voiced by Vicki Lewis), the voice of love and compassion; Bellicus (voiced by Kevin Conroy), the voice of rage and aggression; and Ben, the voice of reason. All three speak in unison when Alien X speaks. In order for Alien X to perform any action, including but not limited to simple movement and transforming back into Ben, two thirds of Alien X's personalities must agree to do so. As both Serena and Bellicus have been arguing for an eternity, and before Ben had no tiebreaker, getting them to focus on any present task is difficult at best, leaving the body of Alien X frozen in place while Ben attempts to convince them to act. Alien X first appears in "X = Ben + 2", where Ben uses the form to stop a flood caused by a broken dam. After much fruitless argument, Ben eventually convinces them to let him leave and resolves to never transform into Alien X again.

Big Chill

Big Chill is a Necrofriggian ("necro", meaning death, and "frigid", meaning very cold) from the planet Kylmyys (the Finnish word for coldness). A moth-like alien, Big Chill's wings and antennae can fold up into a cloak of sorts, giving it the appearance of a phantom. It can become intangible and invisible, fly, has superhuman strength despite its frail appearance, and can breathe freezing vapor. It can also freeze the objects it phases through at its discretion. Counter-intuitively, Big Chill is easily capable of withstanding extreme heat, at one point drinking molten metal directly from a massive smelting cauldron. It first appears in "Kevin's Big Score" to chase down Kevin after he stole the Rustbucket.

It is revealed that Big Chill's species asexually reproduces, laying eggs once every eighty years. They build a nest out of digested metal, from which their offspring hatch. The newborn Necrofriggian live in space, feeding on solar plasma. When Ben goes through this reproductive cycle, Big Chill takes over his personality, causing Ben to unwillingly transform into Big Chill to carry out his task.

Brainstorm

Brainstorm is a Cerebrocrustacean (a play on "cerebrum" and "crustacean") from the planet Encephalonus IV (a play on "encepha-", a prefix referring to the brain). Brainstorm is a genius crustacean alien with the ability to control electrical energy and project force fields around himself and others through thought, accomplished by opening the exoskeleton plates on his skull. In this form, Ben speaks with much greater diction and with a British accent. He first appears in "Pier Pressure" to battle Ship. Brainstorm is Ben's first accidental transformation in the new series, and the first alien that Ben thinks up a name for (Ben simply shouts out the names of the other aliens upon using them). However, unlike the accidental transformations in the previous series, this one was caused by the dock shaking and causing the Omnitrix to cycle to Brainstorm instead of the one he chose. Brainstorm also can shoot lightning from a distance to its target.

Chromastone

Chromastone is a Crystalsapien from the planet Morotesi (which is the Turkish word for ultraviolet). Chromastone is a silicon-based life-form, able to absorb energy (like a conductor) and channel it into laser blasts or less-intense natural light. He can also allow it to pass harmlessly through his body. Chromastone can seemingly produce blasts without having to absorb energy, though it may be due to absorption of radiant energy (like sunlight, or streetlamps) or just ambient energy. He has superhuman strength and is nearly invulnerable to harm; you may say that he is invincable. He first appears in "All That Glitters" to stop a group of zombified schoolgirls.

Echo Echo

Echo Echo is a Sonorosian from the planet Sonorosia (both a play on sonar). He is a small white alien whose body is a living amplifier. He can scream at ultrasonic frequencies capable of overloading machinery and stopping projectiles in mid-flight. He also has the ability to duplicate himself, not unlike Ditto, but different in that the clones aren't linked in any way, allowing entire groups to be knocked out without hampering the rest. By combining these two aspects, Ben can create the "Wall of Sound", where he and his clones can redirect projectiles back to their source by bouncing them off of strategically placed clones.He can also use echolocation, and can channel vibrations to enhance his power, . and transmit sound waves through speakers (such as phones. He first appears in "Ben 10 Returns" when Ben fights a robotic dragon controlled by the Forever Knights.

[edit] Goop

Goop is a Polymorph (a word meaning "many shapes") from the planet Viscosia (a play on "viscous").[50] He is a shape-shifting, self-regenerating green blob that weighs 200 pounds. Goop's slime is controlled by a UFO-like machine over his head, which is also where Ben's voice comes from. The UFO can cause the slime to take any shape and even hover off the ground. However, if the UFO and the slime are separated by even a short distance, the slime will become inert until the UFO recollects it. Goop's slime can be made acidic[51] . Goop first appears in "The Gauntlet" when Ben battles an alien robot.

 Humongousaur

Humongousaur is a Vaxasaurian ("sauria" being a clade of lizards), a humanoid dinosaur alien from the planet Terradino (a play on "terra", Latin for earth, and "dino" from dinosaur). Standing at about twelve feet tall, Humongousaur has great strength and a thick layer of skin which provides vast resistance to injury. He also has the power to increase his own body size and mass, growing up to one hundred feet in height. His strength increases as he grows, and his dinosaur features become more pronounced, growing Stegosaur-like plates on his back and spikes on his tail. His first appearance is in "Ben 10 Returns" when Ben fights a swarm of DNAliens.

 Jetray

Jetray is an Aerophibian (a play on "aero" for air and "amphibian") from the planet Aeropela. Jetray is a manta ray-like alien capable of flying and swimming faster than the speed of sound. He can fire neuroshock blasts from his eyes and tail. Jetray first appears in "Everybody Talks About the Weather" when Ben needed to chase after Alan Albright, a human/Pyronite hybrid.

 Spidermonkey

Spidermonkey is an Arachnichimp (a play on arachnid and chimpanzee) from the planet Aranhascimmia ("Aranha" which is the Portugese word for "spider", and "scimmia", which in Italian means monkey).[54] As his name suggests, he is a six-limbed monkey-like alien. He has superhuman agility and, like a spider, can spin webs that he can swing from or create nets from his tail, and stick to walls. When Ben transforms into Spidermonkey, he talks in an excited, childish tone and displays mischievous characteristics with occasional monkey-like screeching. He is first seen in "What Are Little Girls Made Of?" to fight his grandmother Verdona Tennyson.

Swampfire

Swampfire is a Methanosian from the planet Methanos (referring to Methane). Swampfire is a plant-like alien with a fire-patterned head. He is described as a living swamp. He has superhuman strength, vast regenerative powers, the ability to control plant life through a type of gas, and the ability to shoot fire from his palms, which can also be used to launch his body for flight (similar to Heatblast). The fire is created by igniting methane naturally produced within his body, which makes him stink. He can also produce seeds which quickly grow into vines that he can control. His regenerative ability allows him to alter his own body, such as tunneling underground in vine form, growing his feet to root himself into the ground, heal the limbs of others, or passing through prison bars. Swampfire is Ben's first transformation when the Omnitrix is recalibrated in "Ben 10 Returns".