Elder Toguro is the older of the Toguro Brothers, though he's comically tiny—so small he usually just rides on his younger brother's shoulder. He's got a mean streak way nastier than Younger Toguro's, and is one of the few people who can actually get under his brother's skin. His whole motivation in the Dark Tournament was straightforward: kill Urameshi's team and their allies, no exceptions. He ranked 11th in Japan's second character popularity poll with 421 votes.
Before things got dark, Elder and Younger Toguro ran a dojo together with Genkai. After Kairen attacked it, all three jumped into the Dark Tournament. They won, but the brothers got ambitious—they wanted to become demons themselves. That wish eventually came true, and both ended up working under Sakyo.
What makes Elder Toguro genuinely creepy is his ability to completely reshape his body. He can move his organs around, morph himself into weapons for his brother to use, and pull off stuff like turning his fingers into drills or his arm into a sword. He can even transform parts of himself into tiny puppet versions of people. Add in near-total regeneration and basic immortality, and he's harder to kill than he has any right to be for someone who rides on his brother's shoulder.
He shows up early on, fighting Kuwabara and Yusuke alongside the other Toguro and their leader Gonzo—where he literally becomes a sword so his brother could fight. After that he mostly sticks to the background until the tournament's final rounds.
Content compiled by AnimeList.moe from publicly available sources.