Kyubey being Kyubey
Analysis: Spelling conflicts
The odd Japanese spelling of Kyubey's name has contributed to many alternative Latin-character spellings. The three supported by official materials are "Kyubey", "Kyubee", and "Qbey".
"Qbey" appears written in runes in episode 11.
Kyubey "Cute Alien" Model
In episode 2 of Ground Defense Force! Mao-chan, a 2002 anime that shares certain superficial traits with Madoka, one of them is a very Kyubey looking alien. In this anime, these aliens are considered so cute that the world has a difficult time defending against the alien invasion, because of public opinion that this would be "bullying."
However, the similarity in appearance is coincidental. Ume Aoki stated in the BD 1 episode 2 audio commentary that Kyubey's design wasn't based off any character.