In the original Mirage Comics storyline for Teenage Mutant Ninja Turtles, April O'Neil was a skilled computer programmer and assistant to a famous yet nefarious scientist, Baxter Stockman.

April and the Turtles retreated to a farm house in Northampton, Massachusetts, to recover and during this time she suffered recurrent nightmares about the Foot Clan's attack.

In Volume 2 of the TMNT comics, April was attacked by a huge robot controlled by the brain of her former boss, Baxter Stockman, and injected with nanobots.

Although the trip helped April cope with her demons and led to her eventual return to New York, her family history remained unexplored.

In the continuity of the IDW comics, April is a very bright science student who interns at Baxter Stockman's genetic laboratory Stock Gen, where her father used to work before a stroke rendered him paralyzed.

April subsequently accompanies or assists the Turtles in their adventures and battles against their enemies, in the course of which she investigates Stockman's clandestine operations and makes an important contact in the Pantheon by incurring the sympathies of one of their members, Aka.

In the dark alternate future of Teenage Mutant Ninja Turtles: The Last Ronin, New York has been conquered by Oroko Hiroto, the grandson of the Shredder and the new head of the Foot Clan, with April leading a faltering resistance movement against him.

Michaelangelo is killed in the final clash with Hiroto, but he leaves Casey and April his journal of Splinter's teachings, and the two are shown making plans to mutate a new quartet of turtles in memory of their fallen friends.

In the 1987 cartoon series, April Harriet O'Neil was altered from her Mirage Studios character and instead was introduced as a television reporter for Channel 6 News.

April quickly became their major link to the outside world since their unusual appearance effectively precluded them from functioning above ground without some sort of disguise.

April's friendship with the Turtles resulted in the opportunity to record exclusive footage of their encounters with Shredder, but despite her intimate knowledge of the details of their lives, she tended to keep her professional news reports about them impersonal and mysterious.

In Florida on vacation, she and the Turtles found a body of water contaminated with a mutagen that made mutants feel youthful, while physically de-aging humans into four-year-old versions of themselves.

April could usually be found wearing a distinctive yellow jumpsuit — modeled on that of Fujiko Mine in Lupin III Part 2 — with white boots.

However, she was no longer cast as a news reporter like in the original animated series, with her role now being similar to that of the Mirage Studios character: again, she served as an assistant to Baxter Stockman until his Mouser experiments got out of control, and after the Turtles saved her she became a faithful friend, ally, and "big sister" to them.

In the seventh and final season, she dons a yellow-and-black jumpsuit based on the TMNT film and carries a tantō sword to further perfect her fighting skills.

At one point, she became psionically linked with a female mermaid-like mutant who had telepathically shown her the hardships of her childhood and that the few of her kind were on the verge of extinction.

In addition to her recently developed ninjutsu skills, April is incredibly intelligent, smart and resourceful in complex scientific fields; similar to her good friend Donatello.

Her shoulder-length bright red hair with flowy bangs is tied with a white ponytail holder which becomes undone, at times, if she is under great stress or rage.

Unlike her previous counterparts, she is a 16-year-old teenage girl and possesses exceptionally strong psychic powers, which she eventually learns to develop more and increase drastically throughout the fourth season.

In Rise of the Teenage Mutant Ninja Turtles: The Movie, April starts going to college studying journalism similar to previous portrayals.

She was a television reporter working for Channel 3 news under Charles "Chuck" Pennington, doing an investigative series on mysterious thefts in New York City whose culprits vanished without a trace.

One night while leaving work, she is accosted by teenage thieves in league with the Foot Clan, but the Turtles appear and save her under the cover of darkness.

Though afraid at first, April eventually comes to regard the Turtles and Splinter as friends, even letting them stay in her apartment after the Foot Clan discovered and destroyed their sewer dwellings.

She grows extremely close to the four brothers: Michelangelo, who initially confesses to having a crush on April, later addressing her as "Sis," indicating the role she has come to occupy in the Turtles' family.

April takes up several forms of ninjutsu training from Splinter, purchasing a slim black-and-yellow jumpsuit of armor from Japan, and becoming quite skilled in the use of a katana.

[9] During the film, she is again cast as a reporter for Channel 6 News and it is revealed that not only was April's father involved in the creation of the turtles as his experiments created the mutagen that turned them into what they are now, but that the young April (portrayed by Malina Weissman) was responsible for the Turtles and Splinter escaping the destruction of the lab where they were created when she released them into the sewers after the lab was destroyed by her father to prevent Shredder and Eric Sacks getting access to the mutagen.

April made a live-action appearance in the TMNT: Coming Out of Their Shells musical tour played by Sherie Rene Scott whose role was to incite the live audience to interact with the stage performers and encourage the Turtles when needed.

April has appeared in most of the TMNT video games, usually as the damsel in distress who has been captured by Shredder (or by Karai in case of SNES version of Teenage Mutant Ninja Turtles: Tournament Fighters[18]).

April appears as a playable character in the 2021 fighting game Nickelodeon All-Star Brawl, utilizing her design from the 1987 animated series,[20] voiced by Abby Trott.

After helping the turtles defeat the Statue of Tyranny and Super Shredder, she is rehired by Fenwick, though due to him hiding during the battle, he mistakenly gives the credit to the Punk Frogs.