Eudial (called Eugeal in the English dub) leads the Witches 5, a group of servants working under Professor Tomoe. She's the oldest member and the one Tomoe clearly favors, which breeds serious resentment—especially from Mimete—among the others.
What makes Eudial stand out is her genius for invention. She cobbles together weapons and tech from everyday objects with remarkable ingenuity; her signature Fire Buster weapon, for instance, is literally built from a blender and vacuum cleaner hose. Using this same knack for machinery, she rigged up a computer capable of tracking Talisman holders and managed to snatch two of them before Sailor Pluto shut her down. The other Witches call her "Chief," reflecting her leadership status.
Personality-wise, she's calm and collected—except when she's behind the wheel. Her driving is catastrophically bad, constantly nearly mowing people down, partly because the car keeps emerging from underground tunnels in completely weird spots. She eventually booby-traps the unfinished Marine Cathedral and carries a deadly shoulder-mounted flamethrower (later upgraded) into combat.
Her downfall comes when she loses those two Talismans to Sailor Pluto. Furious, she tries to escape in her car only to discover Mimete's sabotage: the brakes are gone and the vehicle is packed with snails. The car careens over a highway overpass into the ocean, killing her instantly.
In the manga, she's a different beast entirely. There she poses as Yuko Arimura, teaches Good Etiquette at Infinity Academy's Philosophy division, and leads students on a "Mount M" retreat to remove their Hostes. Sailor Mars and Sailor Jupiter confront her there; Mars's Snake Fire attack transforms her into something Gorgon-like with a black star on its forehead before Sailor Moon finishes her off.
Content compiled by AnimeList.moe from publicly available sources.