Mutant Ninja Turtles Gaiden, also known as MNT Gaiden or MNTG for short, is a long-running fan webcomic written and illustrated by Tigerfog. It has been running since 2004, and still updates intermittently. At over 800 pages, MNT Gaiden already rivals entire volumes of official TMNT comics in sheer story length. Though MNT Gaiden is purely a fan work and is not licensed by Mirage Studios or Viacom, it is one of the more famous fan works, having managed to attract its own fan base and forge its own influence.

The comic's setting is an alternate universe branched off of the Mirage continuity's volume 1 with influences from both the Image continuity and the 2003 cartoon, and its character designs are patterned after the 2003 cartoon, and the overall visuals adopt additional shōnen manga influences with sound effects written out in katakana. Compared to most other TMNTincarnations, MNT Gaiden is far darker and more brutal, with stronger language and more graphic violence. MNT Gaiden also explores and deconstructs topics of mental illness and ethical dilemma in ways that greatly blur the distinction between hero and villain.

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