Lhii was a fictional Ta-Matoran that Vakama told stories of, as a Turaga while on Mata Nui. In these stories, he used Lhii as a way of indirectly keeping memories of his mentor, Lhikan, alive. Lhii was said to be all yellow and wore a Kanohi Pakari. In the stories, he was a legendary lava surfer said to be in the clan of Jaller, and died while surfing. He was remembered by all Ta-Matoran, but after hearing the Metru Nui tales, they now know he never existed.
Lhii's character, not just through his adventures, was very similar to Lhikan in many ways. For one thing, their names are very similar. Plus, they were both good at lava surfing, which hints at Lhikan's expert ability to not just surf on lava, but on other surfaces as well. Finally, Jala was said to be part of the "clan of Lhii", which hints of Lhikan's original mask being passed on to Jaller.