Jennika

She was introduced in issue #51 of the first IDW Publishing comic book series in 2015, and was developed by Tom Waltz and franchise co-creator Kevin Eastman. She was designed by series artist and writer Sophie Campbell. Jennika is the second female mutant turtle character in the franchise's history, after Venus and preceding Lita the year after her mutant form first appeared.

Jennika
Textless cover variant of Teenage Mutant Ninja Turtles: Jennika #1. Art by Brahm Revel.
Publication information
Publisher	IDW Publishing
First appearance	Teenage Mutant Ninja Turtles #51 (2015)
Created by	Tom Waltz Kevin Eastman Sophie Campbell
In-story information
Species	Human turned mutant turtle
Team affiliations	Foot Clan (formerly) Splinter Clan
Partnerships	Leonardo Donatello Raphael Michelangelo Splinter Casey Jones (ex-boyfriend) Sheena (lover) Venus
Abilities	Versed in ninjutsu, stealth, espionage and various hand-to-hand and ranged combat disciplines Superhuman agility, speed, and strength

Jennika is depicted as a human assassin for the Foot Clan, though she eventually allies herself with the Teenage Mutant Ninja Turtles. After being severely wounded by Karai, Jennika is transformed into a mutant turtle when Donatello uses Leonardo's blood to give her an emergency blood transfusion. As a mutant turtle, she wears a yellow mask and wields tekkō-kagi.

Starting from issue #117, Jennika was revealed to be bisexual, forming a new romantic relationship with one of the mutants of Mutant Town, the pig mutant Sheena, due to their shared love of music.

In addition to the mainline Turtles comic book series by IDW, Jennika has also been the lead in the three-issue miniseries Teenage Mutant Ninja Turtles: Jennika in 2019, which was followed by the six-issue sequel miniseries Teenage Mutant Ninja Turtles: Jennika II in 2020.

Jennika was introduced in the issue #51 of IDW Publishing's ongoing Teenage Mutant Ninja Turtles series, published in 2015. Franchise co-creator Kevin Eastman said of the character:

What was interesting when we evolved into the character Jennika [...] my focus is on the comic books with Tom Waltz and IDW and it's always story first, story-centric. So when we introduce a character in issue #51 named Jennika, we really like her and we knew that if the fans liked her as much as we did, she can continue as part of the family. She got more and more popular and so for about 30 issues we wanted to evolve her into this female turtle character.

Debuting as a human character, Jennika is transformed into a mutant turtle in issue #95 of the IDW series, published in 2019.

In 2019, Jennika featured in her own three-issue miniseries by IDW, titled Teenage Mutant Ninja Turtles: Jennika, by artist and writer Brahm Revel. A six-issue sequel miniseries, Teenage Mutant Ninja Turtles: Jennika II, was published in 2020.

Jennika is set to make a cameo role in the upcoming 2024 comic book issue Teenage Mutant Ninja Turtles: Saturday Morning Adventures #12 also distributed by IDW which is based around the 1987 TV series. This is where the '87 turtles enemy Mr. Ogg, transports Ninja Turtles from across the Multiverse to compete against the '87 Turtles, each representing a single universe, consisting of the Mirage/Image, 2003 series, IDW, 2012 series and Rise of the TMNT universes, with Jennika representing the IDW Universe.