Ma-Ti was a member of the Planeteers team from Captain Planet. He represented South America and had a ring with the power of Heart.
The TGWTG.com version of Ma-Ti was played by Bhargav Dronamraju, and made his first appearance in the Nostalgia Critic's Captain Planet review. In this first appearance, Ma-Ti let it slip that he was of Indian descent, and not actually from South America. Over the years, he appeared in many videos including the the brawl, Kickassia and finally he seemingly met his end at the hands of Malachite in Suburban Knights. But at the end of the video The Nostalgia Critic is told by Linkara about The Necronomicon the Book of the Dead which has the ability to bring the dead back to life. Hinting that Ma-ti might come back to life.
However, the Critic was too lazy to find the Necronomicon, so Chester A. Bum was sent in his place. Chester failed, and the Critic is left as a relatively empty shell of his former self, though he does not feel remorse for Ma-Ti's death. It was also revealed that it was the Critic that falsely wrote his will and had his cremated remains put into an oatmeal can. While his body was dead, Ma-Ti lived on, as his character survived by taking over Spoony (in an inconsistant security footage where he transfered part of his soul into Spoony during the battle for Malachite's Hand), thought the Critic put him in the care of Dr. Nella and Dr. Elisa after mistaking his warnings as sexual innuendos.
The two female doctors strap Spoony to machine that would read his mind, and after asking him several questions, discovered that Spoony thinks that he is indeed Ma-Ti, though unconsciously. His remains had been sucked into a giant wormhole known as the Plot Hole, sending him to the Jovian Moons of Europa. As this occurs, the Critic's computer is taken over by another part of Ma-Ti's character, accusing him of leaving him to die and to "remember". Realizing that Ma-Ti is somehow still alive, the Critic sets out to find his old frenemy by transforming his house into a spaceship with his fellow reviewers as the crew.
Film Brain & Sage, whilst in Spoony's mind, learn that the reason Ma-Ti wanted the Critic to go through the Plot Hole, into the real world, believing that the Critic was so selfish and single minded, he would step outside into reality, destroying the Reviewaverse as a result. Film Brain tries to convince Ma-Ti that the Critic has genuinely changed, but doesn't succeed. It isn't until the Critic deciding to stay inside "The Writers" house and apologises for all that he's done does Ma-Ti see that the Critic has indeed changed, and willingly crosses over.
However, with Ma-Ti at peace, there is nothing to keep the Plot Hole stable, so Nostalgia Critic takes his place as the Hole. But the Critic was replaced by Douchey McNitpick in honor of returning Donnie DuPre back into The Nostalgia Critic.
Bhargav himself has created an elaborate backstory for Ma-ti, which was explained in an episode of Transmission Awesome.