Teenage Mutant Ninja Turtles: The Next Action is the best web American/Japanese animated series, mainly set in New York City. The trailer reveals the turtle's new voices, the animation, and that the theme song of the new show will be a remixed/remade version of the original theme song from the 2003 cartoon. The Turtles' two catchphrase is "Cowabunga" and "Turtle Power". The mutagen combines elements of both 2003 and 2012 cartoons.
Splinter was the pet rat of Hamato Yoshi in Japan who followed the teachings of his owner from his cage. Intelligent for his species, Splinter was able to learn his master's art by mimicking his movements while he practiced. Yoshi became embroiled in a dispute with a fellow ninja by the name of Oroku Nagi, and was eventually murdered by Nagi's brother Oroku Saki. Without a home, Splinter was forced to run away and live in New York's sewers. Due to a traffic accident, four baby turtles and a steel drum of radioactive ooze called mutagen were sent down into the sewer, where they mutated both Splinter and the turtles. Splinter named the four turtles Leonardo, Donatello, Raphael, and Michelangelo and trained them in the arts of ninjutsu, while still raising them as his own sons. After venturing to the surface for the first time, the teenage Turtles discover a alien race called the Utroms who are usually extremely peaceful and non-interfering and responsible for creating and losing the steel drum of mutagen that transformed Splinter and four Turtles. The Turtles befriend the teenage April O'Neil when she has been kidnapped by a street gang called the Purple Dragons. While April was rescued by the Turtles, she becomes their ally as they help her to find out where the Purple Dragons are up to. The Turtles also learn that the Shredder is leading the Foot Clan into tracking down Splinter and his sons to put an end to their clan.
- Teenage Mutant Ninja Turtles - A team of anthropomorphic freshwater turtles who are the protagonists of the series:
- Leonardo - "Leo" is an enthusiastic student, learning how to be an effective leader for his three often unruly brothers. He wears a blue mask and fights with two katana swords called Niten Ryu. Aside from his sensei, he takes leadership references from his favorite sci-fi series Space Heroes which annoys Raph to no end. He also has a crush on April which his brothers all tease him about. He is especially fond of Karai, with whom he entertains a brother-sister relationship. This incarnation of Leonardo is depicted with a facial expressions and mouth are also very similar to Shoutmon from Digimon Fusion.
- Donatello - "Donnie" is in charge of the design and manufacture of all of the tools and weapons in the Turtles' arsenal, and he is also a gifted hacker. He wears a purple mask and fights with a rokushakubo which converts to a naginata. This incarnation of Donatello is depicted with freckles and a gap with braces.
- Raphael - "Raph" often lets his impulsiveness get in the way of rational thinking. He wears a red mask and fights with two sai. This incarnation of Raphael is depicted with a lightning-shaped scar on his left shoulder.
- Michelangelo - "Mikey" loves video games, skateboarding, pranks, comics, horror movies and pizza. He wears an orange mask and fights with two nunchaku, which convert into kusarigama.
- April O'Neil - The 16 year-old singer who likes to sing a pop song, play video games, watch Space Heroes, and eat pizza. This incarnation of April O'Neil is African American and is depicted with a facial expressions and ponytails are also very similar to Iris from Pokemon.
- Splinter - Splinter is the mutant rat leader of the entire family, and serves as a father figure for the Turtles. He once was a pet for a renowned martial artist, Hamato Yoshi in Japan. It was from watching Yoshi that Splinter first learned the art of ninjitsu which he then passes on to the Turtles. Splinter often acts as much as a spiritual guide and counselor to the team as he does their teacher. While he does not wield a traditional Japanese weapon, Splinter carries a cane which he can utilize as a weapon (like a bo staff) with fierce proficiency. Unlike the previous animated series, the Turtles often refer to Splinter as their father, rather than their master.
- Foot Clan - A ninja organization that is led by the Shredder.
- Oroku Saki/Shredder - One of the primary antagonists of the series and leader of the Foot Clan. Once friends in Japan, Oroku Saki and Hamato Yoshi parted ways when both fell for Tang Shen who ultimately chose Yoshi. Saki's jealousy turned to anger and hatred, especially after Yoshi and Shen fell in love each other. Rather than fight Saki honorably, Yoshi followed Shen's plan to leave for the United States. Saki followed them to New York City, where he first murdered Tang Shen alone in her home, then ambushed Yoshi when he returned, tired from construction work. Yoshi’s pet rat Splinter escaped during the fight, clawing the part of Saki's face, before doing so. Oroku Saki became the Shredder and established the Foot Clan. Saki at sometime before or after this, found an abandoned young orphan girl named Karai. He adopted her and raised her as if she was his own. He taught her everything he knew about ninjutsu and leadership. Years later, Shredder learns that Splinter is in New York. Seeking to finish his business with Splinter, Shredder and his Foot Clan relocate to New York. Shredder almost kills Leonardo, but the distraction of the newly-mutated Draco, Xever and Chris Bradford gave the Turtles the chance to escape. In the same episode, Shredder is shown to have a two pet dogs, Akita named Hachinko and pitbull terrier named Scarface. In another episode, Shredder didn't believe in the Utroms until Karai brought him the robot body of one of the Utroms. As Baxter Stockman gets to work on studying the technology, Shredder assigns Karai to learn more about the Utroms so that he can use whatever information is gathered about them.
- Karai - A rebellious teen member of the Foot Clan and an expert kunoichi who stirs up trouble for the Turtles.
- Hun - Shredder's right hand, and leader of the Purple Dragons, an urban street gang that Shredder sometimes utilizes. He constantly seeks the Shredder's approval and leads the Foot into battle against the Turtles. He is a large, hulking bully, powerful but fast and very skilled in martial arts.
- Chris Bradford/Dogpound - A famous martial artist and secretly a member of the Foot Clan, Chris Bradford is ordered to New York with Xever to find Splinter. After his first encounter with the Turtles, he befriends Michelangelo on a social media website in an attempt to entrap the Turtles, going so far as to teach Mikey his secret kata "The Red Tiger". Bradford later captures Mikey and baits the Turtles to rescue him and lead the Foot to Splinter. However, the plan fails after Splinter recognizes the 'Red Tiger' move during the Turtles' sparring. Bradford is defeated by Mikey's use of the 'Red Tiger' before he and Xever are flushed down the sewers. In one episode, Bradford and Xever go after the Turtles again and are exposed to mutagen. As Bradford was previously bitten by Shredder's pet Akita Hachinko, the mutagen transforms him into Dogpound, a spike-backed dog-like mutant with a large left arm, heightened senses, and super-strength. His human form appears to be modeled after famed martial artist and actor Chuck Norris.
- Xever/Fishface - Xever was an imprisoned Brazilian street thug until Shredder and Hun freed him and indoctrinated him into the Foot Clan. Shredder orders this ruthless, accomplished fighter to assist Chris Bradford in finding Splinter. During a battle in one episode, Xever is exposed to mutagen. As Xever previously touched an exotic fish at a Chinatown Marketplace, the mutagen transforms him into the fish-like mutant Fishface. After his transformation, Fishface lives in the waters within Shredder's hideout. In another episode, Baxter Stockman creates a water-breathing rig for Fishface and mechanical legs that Baxter tries to get working. In the episode "Tales of Leo", Fishface gains full control of his robotic legs and bites Raph with venomous fangs, causing Raph to experience delusions, fever, and nausea.
- Draco/Finlizard - Draco was a Australian rock star until Shredder indoctrinated him into the Foot Clan. Shredder orders this tough, powerful fighter to assist Chris Bradford and Xever. After his first encounter with the Turtles, Draco flirts with April O'Neil. It is because of that April dumped Leo for Draco until he saved her from the Foot. During a battle in one episode, Draco is exposed to mutagen. As Draco previously touched gently his pet green basilisk, Dragon, the mutagen transforms him into the lizard-like mutant Finlizard with color vision.
- Baxter Stockman - An inventor who plotted revenge against a company called TCRI after he was fired for spilling copier toner. A running gag is that the Turtles mispronounce his name. The Turtles first encounter Stockman in rudimentary battle armor, while he attempts to break into a building. The Turtles defeat him, but Stockman obtains Donatello's T-Pod, which contains a military-grade artificial intelligence chip, and incorporates it into his battle armor. The next time the Turtles run into Stockman, his battle armor has upgraded itself. Eventually, the Stockman battle armor and the T-Pod merge into a destructive robotic being, which Mikey dubs "The StockmanPod". The StockmanPod defeats the Turtles, causing them to flee. Using wisdom from Splinter about 'fighting the person inside the armor', the Turtles engage the StockmanPod again, and make use of a beehive to cause the StockmanPod to fall off a building. The Turtles deactivate the T-Pod and throw Stockman in the dumpster again. Following the incident with the M.O.U.S.E.R.S., Hun, Dogpound, and Finlizard bring Stockman to Shredder. Shredder threatened to kill Stockman for interfering with his plan to kill the Turtles, but spares him and comments on how his intelligence could be useful. In "TCRI", Baxter creates a water-breathing gear and his prototype mechanical legs for Fishface. After Karai returned to Shredder's hideout with the Utrom exosuit and the controls to it, Baxter Stockman gets to work on studying the machine so that he can get Fishface's mechanical legs operational. In "Tales of Leo", Baxter Stockman gets the Utrom technology that he uses to successfully get Fishface's mechanical legs operational.
- M.O.U.S.E.R.S. - Mobile Offensive Underground Search Excavation and Retrieval Sentries (M.O.U.S.E.R.S.) are small robots that were created by Baxter Stockman to steal on his behalf. Stockman programs them to attack anything tagged with his radioisotope spray.
- Foot Ninjas - The foot soldiers of the Foot Clan.
- Foot Elite - The foot warriors of the Foot Clan served as the bodyguards and field leaders.
- Foot Techs - The foot technicians of the Foot Clan.
- Purple Dragons - A street gang that has been extorting shop owners for protection money and have become allies with the Foot Clan. The Purple Dragons were led by Hun, Xever, and Draco, but Dogpound took over since Xever's mutation into Fishface.
- Chan - A skinny and young Purple Dragons member who is apparently the leader and uses a butcher knife as weapon.
- Ratsu - A fat and bald Purple Dragons member with a moustache. He uses a mace.
- Zira - A female Purple Dragons member with a red spiky hair. She uses a dagger.
- Frank - The biggest and strongest of the six Purple Dragons with a black mohawk. He doesn't use a weapon.
- Julian - An African American Purple Dragons member who uses a spear.
- Erik - A Purple Dragons member with a goatee. He uses a sabre.
- Triceratons - The Tricerations are a race of saurian aliens that resemble a humanoid Triceratops from their homeworld in Milky Way Galaxy. They have advanced technology, a strong government, and gladiatorial battles. For likewise unexplained reasons, the Triceratons have been in military conflict with the Orc Soldiers.
- Lord Saurias - The prime leader of the Triceraton Republic who planned to take over Earth.
- Commander Hornix - The military commander of the Triceraton Republic. Hornix is the counterpart of Colonel Borc when it comes to military matters.
- Lieutenant Onar - The military lieutenant of the Triceraton Republic.
- Orc Soldiers - An Orc Soldiers are a race of aliens that resemble an orc who lived in Planet Mor'Val. Their entire culture is geared towards war and conflict with a definite tendency towards aggression and hostility in regards to other species. Their numbers are organized into a strict hierarchy, with power/prestige directly linked to military rank; their supreme leader is Colonel Borc.
- Colonel Borc - A ruthless leader of an Orc Soldiers. He was aided by his assistant and underling, Donae.
- Donae - Donae is an assistant and underling of Colonel Borc.
- Sykes/Ogreman - Sykes is a thug who stole a blue diamonds from the jewelry store. During his plan to intrude the Utroms' TCRI building, he fell into the mutagen and mutate into a monstrous creature that resemble an ogre that Mikey simply dubs "Ogreman". Ogreman attacks the Utroms until he is defeated by the Turtles. During the battle, Ogreman escapes, vowing to get revenge on the Turtles later.
- Utroms - Utroms are an alien race from the Milky Way Galaxy that resemble a brain and pilot robotic bodies and are responsible for bringing mutagen to Earth.
- Mortu - Mortu was the captain of the Utrom ship that crashed on Earth. After the crash, he remained the field-leader of the marooned Utroms, and worked as their liaison to the Humans. In the modern day, this makes him CEO of the front company TCRI. His name is "Utrom" backwards.
- Dr. Juniper - Dr. Juniper is the beautiful Utrom scientist who is Leatherhead's adoptive mother and Mortu's assistant.
- Utrom Grand Council - The Utrom Grand Council is a supreme leader of the Utroms on Earth.
- Leatherhead - Leatherhead was originally an exotic pet owned by a young boy until his parents found out and flushed him down the sewer, somehow ending up in an Utrom lair. After being exposed to the same mutagen that would eventually change the Turtles, Leatherhead became a massive, humanoid crocodile. He lived with Dr. Juniper and other Utroms whom he considered his family.
- Traximus - Traximus was a noble warrior of the Triceraton Republic who believed that its old virtues should be restored. He spoke to the council and, at the orders of the tyrannical Lord Saurias, found himself in the dungeons with warriors taking part in "The Games". He was left to rot in his despair until he was bested by Leonardo, who spared his life with honor. Inspired by this act of kindness, Traximus regains hope that the current dictatorship can be overthrown, and leads the other gladiators to freedom in the midst of the chaos surrounding the Turtles' escape.
- Zog - Zog was one of the Triceratons teleported to Earth mid-battle with the Orc Soldiers over Honeycutt's teleporter. However, while the other Orc Soldier and Triceraton forces are returned home by the Utroms, Zog became lost in the sewers, and was found by the Turtles choking to death from lack of his native air. Believing the Turtles to be Triceraton-allied military leaders, Zog pledges his undying loyalty to them and later "General" Splinter, in particular befriending Michelangelo.