Mustachios

The Pistachios are supporting characters of "The Annoying Orange" and the first five mustachios in the series who first appeared in "Mystery of the Mustachios".

They were, in reality, pistachios who were wearing mustaches to avoid getting eaten. Orange and Pear, however, knew that they were actually pistachios wearing mustaches. Soon after, however, their mustaches began falling off. Four of the "Mustachios" were eaten by Dane Boedigheimer, and the remaining one, assumed to be the leader, was devoured by a caterpillar (or a "pistachio-eating caterpillar").

Since that episode, mustachios have been scattered all around the kitchen and have appeared in many future episodes.

They appeared most abundantly, however, in season 3.

First Mustachios in the Series
They are in both order of their deaths and placement:

Barry: The pistachio with a white mustache and the one on the far left. His mustache became extremely slanted after he sneezed, blowing his cover, as well as those of his friends. Because of this, his shell was ripped off, leaving him "naked". He spoke the second most lines, behind the first one.

Phil: The pistachio on Barry's right. He had a straight brown mustache and insisted that they should have donned sombreros instead.

Bob: The one in the middle. He had a dark blonde mustache.

Peter: Right to middle. He has a black, curly mustache and the deepest voice. He has the fewest lines.

Richard: The pistachio with a grey mustache and seems to be the head of the five. In the end, his mustache stayed on, but still he was eaten by the Pistachio-Eating Caterpillar. He spoke the most of them all.