Some TMNT stuff really isn't for little kids.
In the tabletop role playing game Teenage Mutant Ninja Turtles & Other Strangeness, published in 1985 by Palladium Books, the porcupine is one of many possible templates of mutant species that players can use to design original player characters.
Teenage Mutant Ninja Turtles & Other Strangeness
Available species-specific abilities provided by the game rules for porcupine characters include advanced senses of smell and hearing, being able to climb with their claws, and a body covered with quills. These quills could provide a degree of armor, cause injury to attackers who made physical contact with them, and be utilized deliberately as weapons, either by pulling them out and throwing them as daggers, or causing potentially severe injury when a porcupine body-slams their opponent. Porcupine characters can be formidable fighters.
LIkenesses of the TMNT&OS porcupine template have appeared as later character designs, decades after the RPG book was originally published, and long after Palladium Books eventually ceased its publication.
Spikeback, a recurring enemy appearing in the 2014 video game Teenage Mutant Ninja Turtles: Brothers Unite, strongly resembles the TMNT&OS porcupine, especially from the waist up, and his character art even stands in a similar posture and viewing angle, albeit mirrored horizontally. Other than resemblance, no specific direct design link to the TMNT&OS template has been confirmed.
First appearing in Teenage Mutant Ninja Turtles issue #101, published in 2019 by IDW Publishing, Diamond is a former human who mutated along with up to thousands of others after Old Hob detonated his mutagen bomb in Union Square Park and wind blew fallout over a part of Manhattan's East Side that would subsequently be quarantined and walled off as Mutant Town. For a time, Diamond worked for Hob as one of the Mutanimals' enforcers in Mutant Town, but she proved too brutal towards her fellow mutants, and her employment was eventually terminated by Sally Pride.
Diamond was designed by longtime TMNT writer-artist contributor Sophie Campbell, drawing inspiration from the TMNT&OS porcupine.