Michelangelo, nicknamed Mikey or Mike, is a superhero and one of the four main characters of the Teenage Mutant Ninja Turtles comics and all related media. Characterized as the most naturally talented of the four brothers, Michelangelo prefers leisure to training martial arts. Aside from being the most jocular and energetic of the team, he is shown to be rather immature; he is known for his wisecracks, quick-wit, optimism, and love of skateboarding and pizza. He is usually depicted wearing an orange eye mask. His signature weapons are a single or dual nunchaku, though he has also been portrayed using other weapons, such as a grappling hook, manriki-gusari, kusarigama, tonfa, and a three-section staff (in some action figures). He is commonly portrayed in media as speaking with a California accent and is most associated with the "Cowabunga" expression that became a pop culture phenomenon.

Michelangelo was given a much bigger role in the 1987 animated series and subsequent series and films, directed at a younger audience, than in the more serious Mirage comic books, which were aimed at an older audience. He often coins most of their catchphrases, such as "Cowabunga!" and "Booyakasha!" in the 2012 series.

Like all of the brothers, he is named after an Italian Renaissance artist; in this case, he is named after Michelangelo. His name was originally spelled "Michaelangelo" by the creators, possibly spelling his namesake's name wrong by confusion with "Michael". In the Mirage comics, all four of the Turtles wear red masks, but to tell them apart, he was given an orange mask in subsequent media.

An alternate universe version of Michelangelo was also the main protagonist in the five-issue miniseries The Last Ronin.

Comic books Mirage Comics In the Mirage comic books, Michelangelo was initially depicted as fun-loving, carefree, happy-go-lucky, and, while not as aggressive as Raphael, always ready to fight. He is much more serious-natured in the comic book than in the film incarnations, which have labeled his character a permanent "dude" talking teenager. It was Michelangelo's one-shot in this series that fleshed out most of the traits that have become synonymous with the character, such as his playfulness, empathy, and easygoing nature. In the one-shot story, Michelangelo adopts a stray cat (which he names Klunk) and also stops thieves from stealing toys meant for orphaned children.

After their defeat at the hands of the Foot Clan, the Turtles, Splinter, April O'Neil, and Casey Jones retreat to a farmhouse in Northampton, Massachusetts which used to belong to Casey's grandmother. While there, April is worried to note that Michelangelo is not himself. He spends his days in the barn taking out his aggression on a punching bag. A scene shows him lashing out at his surroundings and repeatedly punching the wall of the barn until it breaks, then collapsing on it despondently, anger spent. The end of the story implies that Michelangelo's sorrow and frustration have been resolved, as subsequent issues restore Michelangelo's more relaxed, optimistic personality.

It is during the group's time at the farm we learn that Michelangelo also has an interest in comic books, specifically ones involving superheroes such as "The Justice Force" (comic book heroes based on the Justice League and the Fantastic Four). He also finds solace in writing fiction and has produced a story depicting himself as a rōnin in Feudal Japan (vol. 1 Issue #17).

In the story arc City at War, Michelangelo instantly bonds with Casey Jones' adopted daughter Shadow, who nicknames him "Rooish". In the second volume, the Turtles decide to try to live apart from one another. Michelangelo, the social creature that he is, moves in with April and Casey so that he can be close to Shadow. Throughout the first two volumes, Michelangelo seemed to act as the peacemaker of the team. These stories also laid the foundations which demonstrated his closeness with his brother Donatello, their laid-back natures separating them from the more contentious Leonardo and Raphael.

In Volume 4, Michelangelo gets a job as a tour guide showing alien visitors around Earth. His first (and only) tourist is the Regenta (or "princess") Seri of the Styracodon race. Michelangelo convinces Seri to sneak away from her bodyguards so that he can take her on a tour of the northwest coast of the US. Their relationship becomes more intimate, and Seri delivers eggs that will soon hatch into children. Unfortunately, before much time is given for him to settle with this news Seri's bodyguards become aware of his machinations. They attack Michelangelo and transport him back to their homeworld, where he is placed in prison, kept away from Seri and their unborn children. With the help of a Triceraton prisoner named Azokk, he manages to escape and is rescued by a group of Triceratons who came to rescue Azokk. The ordeal results in Mikey's personality taking a very dark turn, having been hardened by the cruelty of the extrajudicial prison and Azokk's death. Upon the Triceratons learning of Azokk's death, they declare war on the Styracodons and carry out a genocidal assault against them. Michelangelo, embittered by Seri's apparent betrayal, joins forces with the Triceratons and gladly aids them in acts of genocide against the Styracodons.

Michelangelo was not given an especially large role in Volumes 1 and 2, did little to advance the plot and was often not portrayed as an especially skilled fighter. His relatively small role was probably due to the need to establish Leonardo's role as "leader" along with the fact that Donatello was Peter Laird's favorite Turtle, and Raphael was Kevin Eastman's favorite.

This incarnation of Michelangelo appeared in the Turtles Forever crossover special voiced by Bradford Scobie.

Image Comics In the comics published by Image Comics, retroactively setting the Mirage Comics series in the Image Universe, Michelangelo's interest in writing is expanded upon and he is established as a writer of fiction and poetry. During this series, Michelangelo develops a romantic relationship with Horridus, whom he credits as his muse in writing. But the relationship would not last, (as the story may have begun after Rapture's death), she started staying with Officer Dragon and had developed an attraction to him; though Dragon did not know it himself. Michelangelo would be heartbroken when Sara dumps him. An early issue has him selling his first poem to a poetry digest. As the comic continued, Michelangelo's career as a writer gradually expanded. In the final issue, he has published his first novel, a romance called "A Rose Among the Thorns". April mentions that the book was already going back for a second printing and that she had heard that Oprah Winfrey loved it, which "practically guarantees that it will be a best-seller." Michelangelo is the only Turtle who did not end up disfigured in some way in this series; Leonardo lost his left hand and had it replaced by a steel cap with a retractable blade, Raphael was facially disfigured after being shot in the face, and Donatello was transformed into a cyborg after being shot and thrown out of a helicopter. Mikey asked Sara for her hand in marriage but was denied. Michelangelo was last seen arriving at the Northampton farmhouse with his family in the final issue.

Archie Comics In the Archie Comics series, Michelangelo was initially presented very similarly to his 1987 cartoon portrayal — understandably, considering that the comic started as an adaptation of the popular animated series. As the series progressed, Archie'''s "Michaelangelo" was presented as more mature than the cartoon version. This version developed also an interest in poetry. During a battle, he was temporarily blinded and later captured by the US military, whereupon he was interrogated and tortured. He was eventually rescued by his family and saved the life of the man who tortured him.

One of his many skills in the Archie comics was the ability to communicate with animals. In a storyline set in the future, Michelangelo is shown to have become an artist whose main job is running an orphanage.

IDW Comics

Michelangelo like his brothers was reincarnated into a turtle after he was slain by Oroku Saki. He is also the youngest turtle as shown in his human form when he was the only baby among his brothers. He is more mature in this incarnation than others, but is still sociable, for example, bonding with the Mighty Mutanimals and with pizza boy Woody Dirkins. Unfortunately, Michelangelo's friendship with Woody waned, as shown in Teenage Mutant Ninja Turtles Issue 15, when Slash frightened Woody and he left a note for Michelangelo stating that he could not handle the troubles that followed them. However, their rift only lasted briefly before once more reuniting in issue 26. Michelangelo is good friends with all Mutanimals but can be unsure about Old Hob, remembering how Hob had been their enemy. Further, Michelangelo was occasionally anxious about them, showing some concern in Issue 68, in which Hob told the Turtles that Slash had been mind-controlled, taken out all the Mutanimals, and helped capture them for the Earth Protection Force, as well as in Issue 70, in which Michelangelo wondered whether Slash would be okay. Michelangelo is also the most sensitive turtle: e.g., in Issue 50 he couldn't handle Splinter accepting the leadership of the Foot Clan. In this incarnation, Michelangelo is romantically interested in Neutrino: Princess Trib instead of Kala based on the 1987 TV series. Michelangelo's kindness found him supporting Donatello's ideas for just about everything, as when Raphael introduced Donatello's tracking device (embedded in a shuriken) in the "Secret History of the Foot Clan". The after-effects of the war left Michelangelo distraught seeing that he was strict with Raphael when they were mourning Donnie's injuries. He also shows signs of intelligence when he decodes ancient Japanese text in the "Ashi no Himitsu" book that tells the secrets of the Foot Clan. Furthermore, he was not afraid to confront Splinter when he had taken the orphans with him to prevent them from training as Foot Ninja. Eventually, he convinced Splinter to listen to him and won their debate. Nonetheless, Michelangelo is still as fun-loving a turtle as in other bodacious versions of himself.

The Last Ronin A darker, alternate version of Michelangelo is also the primary protagonist of the miniseries The Last Ronin. Set in an alternate dystopian future, Michelangelo is the last surviving member of his family after his brothers, Splinter and Casey were slain by the Foot Clan, and after spending over a decade training across the world, Mikey returns to New York seeking to avenge the death of his brothers by killing the Shredder's grandson, Oroku Hiroto. In the miniseries, along with his signature nunchucks, Michelangelo also wields the weapons of his brothers, including Leonardo's katanas, Donatello's bo staff, and Raphael's sai.

Television 1987 animated series Michelangelo's persona became strongly established in the 1987 animated series. He was often seen as a "Party Dude", which, though accurate in the 1987 series (which gave him this title in the theme song), accounts for only part of his personality otherwise. As the "party dude", he usually did not have much input in the team's plans, although he was still just as active as his brothers. He typically spent much of his time joking and socializing with other characters.