The Dizzy Zombies appear in the Season 2 episode Dizzy where they lurk in Pops' subconcious after he gets knocked out from getting too dizzy. Their leaders are a realistic-looking blue jay and raccoon that say that their names are Iacedrom and Ygbir (which are actually Mordecai and Rigby's names backwards, respectively).
They all look different but are all relatively based off of animals like insects and fish, and they all have green and purple features.
Most of them have very posh attire such as top hats, waste coats and canes. They also have british accents to go along with the theme.