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.
Bhargav himself has created an elaborate backstory for Ma-ti, which was explained in an episode of Transmission Awesome.