- Complete Monster: Though this title, originally based on the first cartoon series, started off as a more lighthearted series, that soon changed with the introduction of Mr. Null. Mr. Null was introduced as an unseen tycoon, who enslaved a remote South American tribe to work in some of his mines and tries to dump toxic waste into the ocean. However, we soon discover that Null is actually a demon and has sold the Earth to Queen Maligna and her hordes of insectoid aliens, who plan to destroy humanity and colonize Earth. After the Turtles and their allies the Mighty Mutanimals thwart this alien invasion, Null seeks revenge on them. Null takes control of the Horsemen of the Apocalypse and captures the two groups. Null is planning to make the female members of the Mutanimals into his harem, while the others will be slowly electrocuted to death. Null plans to force Kid Terra, one of Null's former underlings who turned against him, into pulling the switch that electrocutes his enemies, wanting to torment his former employee. After this scheme is thwarted, Null later returns and hires some cyborg assassins, who manage to kill most of the Mutanimals. Null decides to torment Candy Fine, who the girlfriend of Mutanimal Mondo Gecko, by showing her images of the Mutanimals burning in hell. Null then mind-controls her and makes her into his slave. Null had the Mutanimals killed so he can continue what he started, trying to help Maligna destroy the human race. When asked why he does what he does, he responds thusly:
Because death, destruction, these are my favorite things, the things I do best.
- Ensemble Dark Horse: The Future Turtles, especially Don and Raph.
- Hilarious in Hindsight: The comic was easily the darkest book Archie Comics published at the time, which led to several problems with the editorial because of the more adult content. In the 2010s Archie has started publishing several darker titles in order to reach an older audience.
- What Do You Mean, It's for Kids?: Some of the later stories rivaled the Mirage book in terms of grittiness, even though this was the kid-friendly TMNT book. This unfortunately led to problems with the editorial staff at Archie Comics.
- To elaborate: The Mutanimals were brutally shot to death on-panel. Despite time-travel being involved, the team stayed dead. When it was revealed the demon Null was behind it, he disguised himself as one of Candy's deceased friends just to torment her with an image◊ of the Mutanimals burning alive in hell.
- Another storyline had future versions of the TMNT travel to the past, where they met up with Adolf Hitler. They tricked him into committing suicide◊.