Action, Comedy-Drama, Teen Drama, Science Fiction, Urban Fantasy, Martial Arts
- Teenage Mutant Ninja Turtles - A team of humanoid mutant red-eared slider turtles who were hidden ever since their mutations within the sewers of New York City and usually go up to the surface only in the night time.
- Leonardo/Leo - Leonardo is an enthusiastic perfectionist, wears a blue mask, and fights with twin ninjatō swords. He flirted with several girls throughout the series, but his main love interest has always been Karai. He also has a similar personality to his 2003 and 2012 counterparts.
- Raphael/Raph - Raphael is the hotheaded rebel, wears a red mask, and fights with twin sai daggers. He also has a similar personality to his 2003 and 2012 counterparts.
- Donatello/Donnie - Donatello is the brainy pacifist, wears a purple mask, and fights with the single bo staff. He also has a similar personality to his 2003 and 2012 counterparts.
- Michelangelo/Mikey - Michelangelo is the energetic and laid-back party dude, wears an orange mask, and fights with twin nunchucks. He also has a similar personality to his 2003 and 2012 counterparts.
- Hamato Yoshi/Splinter - The adoptive father and teacher of the Ninja Turtles. Constantly seeks the truth about his origins and his true identity. He also has a similar personality to his 2012 counterpart.
- April O'Neil - A Scottish-American girl who attends Roosevelt Hill High School with Casey and befriends the Turtles.
- Casey Jones - A hockey-masked crime-fighter who attends Roosevelt Hill High School with April and befriends the Turtles.
- Woody Dirkins - A large, chubby, teenage pizzeria employee and one of the first friends of the Ninja Turtles.
- Hamato Miwa/Karai - A 16-year-old daughter of Hamato Yoshi (Splinter) and the late Tang Shen and the stepdaughter of Oroku Saki. She is Leonardo's love interest.
- Leatherhead - A humanoid mutant alligator who was adopted by the Utroms.
- Professor Zayton Honeycutt/Fugitoid - Professor Honeycutt is a time-traveler from the year 3005.
- Oroku Saki/The Shredder
- Pimiko - A young Japanese woman who is Shredder's student and second-in-command.
- Baxter Stockman - Baxter Stockman is a teenage scientist responsible for creating Mousers.
- Hunter "Hun" Mason - Hun is Casey's half-brother who is Shredder's muscle and bodyguard, a large Chinese American male with incredible strength, and leader of the Purple Dragons.
- Takeshi/Tiger Claw - Takeshi was a Japanese circus performer who was mutated by the Kraang as a child into a 6 1/2 ft. humanoid mutant Bengal tiger called Tiger Claw with razor-sharp fangs and claws, heightened smell, and superhuman strength.
- Anton Zeck/Bebop - Anton Zeck was a teenage African American male with a purple mohawk and sunglasses, who, along with Owen Rocksteed, is one of Shredder's henchmen. Anton Zeck was later mutated into a mutant common warthog called Bebop upon being spliced with the mutagen filled with common warthog DNA.
- Owen Rocksteed/Rocksteady - Owen Rocksteed was a teenage Caucasian male dressed in the military fashion, who, along with Anton Zeck, is one of Shredder's henchmen. Owen Rocksteed was later mutated into a mutant black rhinoceros called Rocksteady upon being spliced with the mutagen filled with black rhinoceros DNA.
- The series' setting is an alternate universe branched off of the Mirage continuity's volume 1 with influences from both the IDW continuity and the 2012 cartoon.