Uncle Earl is Amber's shrewd uncle from "Carny Knowledge".
After Brian succeeds at getting Amber back, he is just about to call off their relationship in order to soothe his bruised ego, but is interrupted when she calls for her uncle. Uncle Earl warns Brian not to break his niece's heart, as the previous guy who did ended up killed, effectively threatening him into staying with her. Uncle Earl mentions he is both the uncle and ex-boyfriend of Amber.
He is voiced by Mike Henry.