Teenage Mutant Ninja Turtles

Developed by Ciro Nieli, Joshua Sternin and Jennifer Ventimilia for Nickelodeon and based on the characters created by Kevin Eastman and Peter Laird, this CGI-animated incarnation of Teenage Mutant Ninja Turtles ran from September 28, 2012 to November 12, 2017 across five seasons and 124 episodes. It begins at the most human possible starting point: four mutant teenagers step out of their lair for the very first time, blunder straight into a plot by the alien Kraang who are abducting April O'Neil and her father Kirby, and discover that the surface world is far bigger and far more dangerous than their sensei ever let on.

From that first night, the series widens in deliberate, season-by-season steps. Season one is a street-level story of a new team learning to be a team while the Foot Clan and the Kraang close in. Season two escalates into open war, culminating in a full alien invasion of New York in which Shredder allies with the Kraang, the lair is exposed, Splinter is defeated and the city's people are mutated into Kraang hybrids. Season three sends the brothers into exile and then into a three-way conflict between Earth, the Kraang and the Triceratons that forces the unthinkable — Splinter and Shredder fighting side by side. Season four carries the Turtles into deep space and back for the final reckoning with Oroku Saki, and the fifth and final season, retitled Tales of the Teenage Mutant Ninja Turtles, becomes a looser twenty-episode anthology of legends, futures and multiversal detours, including a celebrated crossover with the 1987 cartoon Turtles.

Underneath the mutagen and the pizza jokes, the show is a story about a family that keeps having to redefine itself. Leonardo has to earn the leadership he was handed, Raphael has to learn that anger is not the same as strength, Donatello learns that intelligence cannot solve grief, Michelangelo learns that being the heart of a group is a job, and April and Casey learn what it costs to love people who can never walk in daylight. It is broad, funny, merchandise-friendly children's television that nevertheless keeps raising the stakes until the losses are permanent.

The series argues that family is a choice you keep making, especially after it breaks. Everything in the show's structure supports that thesis: it opens with four brothers who have never been allowed outside and ends, five seasons later, with a team that has lost its father, lost its city, and briefly lost its whole planet — and is still standing because the four of them kept choosing each other.

Its second argument is about growing up as a series of irreversible doors. Most children's action cartoons reset; this one refuses to. Mutations stick, alliances curdle, the Earth is actually destroyed, and Splinter's death is permanent. By letting consequences accumulate, the creators told their young audience something unusually honest: you do not get to be a kid forever, competence is earned through failure, and the reward for growing up is not safety but responsibility.

Finally, it is a story about being a monster in the eyes of the world and choosing to protect it anyway. The Turtles save a city that would scream if it saw them. The show's answer to that loneliness is not acceptance from the world but the found family that already loves them — and, in April, Casey and eventually Karai, proof that the circle can widen.

Where does the series actually end? The most common debate is whether the real finale is 'Owari' — the fourth-season conclusion whose title literally means 'end', in which the Turtles close the Shredder story after Splinter's death — or the twenty episodes of 'Tales of the Teenage Mutant Ninja Turtles' that follow. One reading treats season five as an epilogue: the war is over, so the show becomes a campfire circle of legends, futures and alternate worlds. The less generous reading, common in fan retrospectives, treats it as a coda tacked onto a story that had already finished, which is why 'Owari' is so often called 'sort of the show finale'.

Arriving in 2012, the series was Nickelodeon's flagship relaunch of the property after acquiring it, and it landed at a moment when American action animation was being reshaped by serialised, emotionally continuous storytelling. Its answer was to take a franchise best known for pizza jokes and give it a genuine five-season arc with permanent consequences — a full alien invasion, a destroyed Earth, a dead father figure — while never abandoning the slapstick that sells toys. It was also the first TMNT television series rendered in CGI, and its stylised, cel-shaded-looking approach to 3D became a reference point for how to translate comic-book linework into computer animation.

Critically and among fans it has aged upward. Retrospectives such as CBR's have argued it is 'better than you remember' and 'a high mark for the series that respected its comic book source material', and it is routinely bracketed with the 2003 series as one of the two strongest modern TMNT adaptations. Commentators single out its willingness to treat a young audience with respect — combining frequent humour and clear moral lessons with 'truly compelling moments' — and its Foot Clan storyline is frequently described as the best-executed version of that feud in any incarnation.

Its legacy is also visible in what came after. The show's commitment to distinct, exaggerated personalities for each brother and to a deliberately teenaged voice paved the way for the stylistic risk-taking of 'Rise of the Teenage Mutant Ninja Turtles' and the 2023 film 'Mutant Mayhem'. Retrospectives such as CBR's 'TMNT: 16 Reasons The 2012 Series Ruled' argue it is the template future reboots should study. Showrunner Ciro Nieli has said publicly that he believes the series will return someday — a sentiment that persists precisely because the fanbase has never really let it go.

Seasons one and two established the show's reputation quickly. Audiences responded to the sharply differentiated personalities, the comedy-forward tone and the CGI look, and the second season's escalation into the full Kraang invasion — with the lair exposed, Splinter defeated, Leonardo wounded and New Yorkers mutated — is widely cited as the moment fans realised the series would take real risks. The Foot Clan storyline in particular is frequently described in fan retrospectives as 'top tier'.

Season three, with the farmhouse exile, the Triceraton war and the planet-destroying cliffhanger of 'Annihilation: Earth!', is generally regarded as the series' peak, and the brief Splinter-and-Shredder team-up became one of its most discussed sequences. Season four split opinion: the deep-space material was praised for ambition but criticised for drifting from the street-level identity that made the show distinctive, while its closing pair — 'Requiem' and 'Owari' — drew some of the strongest emotional reactions of the entire run, and Splinter's permanent death remains the show's most debated decision.

The fifth season, 'Tales of the Teenage Mutant Ninja Turtles', is the most contested. Its anthology structure was welcomed by viewers who wanted variety and dismissed by those who felt the story had effectively ended with 'Owari'. The clear consensus high point is the 1987 crossover 'Wanted: Bebop and Rocksteady', which holds an 8.2 rating on IMDb and is routinely named among the best episodes of the series.

The recurring criticism across the run is filler: a substantial number of viewers feel the 26-episode seasons padded their serialised arcs with disposable mutant-of-the-week instalments. The verdict has nonetheless improved over time. Retrospectives describe it as an underrated gem that respected its source material and treated children as capable of handling loss, and it now sits alongside the 2003 series in most rankings of the best TMNT adaptations — a show whose ambitions occasionally exceeded its format, but whose best hours are among the franchise's finest.