Kyubey
Name: Often written as キュゥべえ in katakana/hiragana, with "Kyubey" being the standard English romanization.
Gender: None. Gen Urobuchi clarified on the Blu-ray commentary that Kyubey is genderless.
Kyubey is a familiar—essentially a magical recruiter—who offers to grant any wish a girl desires. The catch? She has to become a Puella Magi and fight witches in exchange. He's the one pulling girls into the whole magical girl system, presenting it as a fair deal while girls are making life-altering decisions based on emotional moments. Whether he's truly altruistic or manipulative depends on who you ask, and that ambiguity is kind of the point.
Content compiled by AnimeList.moe from publicly available sources.