I don't have my earliest avatars archived anymore, but my first one was of a sad rabbit, cropped from this (Pixar's "Presto!" short):
My second was of Randy (South Park), cropped from a still of him standing outside of Whistlin' Willy's, battered and bruised, and staring into the sky with a gaze of hope (I can't seem to find an image of this, but it's from the episode which features him beating up dads at baseball games).
Next up was a thumbs up from Dale Cooper (Twin Peaks):
And finally, for about the past year, assorted images of Saoirse Ronan. I'm probably missing one or two, and I think the chronological order may be a little off, but I can recall using:
Edit: I never did sport an animated avatar. By time I was working on getting my Twin Peaks-based one in order (Cooper giving the thumbs up as lightning flashes), EviLore pulled the plug.