Not a nomination, but I think the avatars for Admin and Adminnemooseus are appropriate in representing their natures and positions. My Minnemooseus avatar (the yawning cat), on the other hand, really has nothing to do with my nature, other than I have a very cute cat.
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Many fine avatars have already been mentioned, but I'll add one that I feel a special fondness for - The wizard cat of AdminPD:
As she would put it - A purrfect avatar.
By the way, I've never placed such in the "Best Admin" topic, but as of recent times, I think it is AdminPD.
Moose
Professor, geology, Whatsamatta U
Evolution - Changes in the environment, caused by the interactions of the components of the environment.
"Do not meddle in the affairs of cats, for they are subtle and will piss on your computer." - Bruce Graham
"The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness." - John Kenneth Galbraith
"I know a little about a lot of things, and a lot about a few things, but I'm highly ignorant about everything." - Moose