Stiltonian

Stiltonians are a race of molluscoid aliens in the anime series Space Dandy.

Introduction
They are known for their fast movements, quick reflexes and gentle nature, being referred as "definitely not biters". In the episode Sometimes You Can't Live with Dying, Baby, Dandy and his friends captured a zombified Stiltonian, confusing it with an unrecorded species due to its unusual color and traits (it was slow, and definitely a biter). It bit Meow, making him a zombie, and this caused a chain of victims to be afflicted with the zombie disease, until - surprisingly fast - the entire universe joined the ranks of the undead.

The episode, however, seems to have been a spin-off, as the universe was back to normal by the next one.