I used to change avatars here more often than I have in recent years. I'm trying to remember which one I used here before my current black cat. It would have been another cat-themed one (most of my CFC avatars in the last 10 years have been cats). The only non-cat avatars I've had in the last 10 years were a political one ("Keep Calm and Heave Steve") during the 2015 federal election, and an old one I use on another forum - Carl Sagan in front of a radio telescope (in homage to the original host of Cosmos while the new series was on... somebody asked me if that was a picture of
me 
).
I've had some others that folks still remember, though, ranging from various smileys (Spud) to Doctor Who (Romana II) to Lolcat character Business Cat.
One or two of the cat avatars I've used here are ones I entered in various avatar contests at TrekBBS - that's a regular activity there, with new contests going 2-3 times/month in all the Star Trek subforums, the general SF/F and media forums, the Miscellaneous forum (aka that forum's version of Off-Topic), the Doctor Who forum (voting is going on right now so wish me luck; the theme is Least Favorite Companion), and probably one or two others.
I've suggested bringing that activity here, just for something fun to try. The winner is determined by voting, and gets the right to host the next contest (which has a theme for people to follow). No tangible prizes, just a nice boost similar to the times when people 'win' the right to start a new serial thread and choose the title.
Winners do not have to change their avatars to the one they entered. They can if they want, and these contests are sources for other people who might want to change their avatar and want inspiration (or just a new one). I've seen some people switch to one of the contest entries from time to time.
Otherwise, over there I've had a grand total of 3 avatars in 13 years. I had to switch from my animated one (a smiley sitting on a tractor while the tractor was being pulled along by the Enterprise; it's bizarre how many people didn't get the joke that the smiley farmer was caught in a
tractor beam) to a static one because XenForo doesn't allow animated avatars. One friend over there said, "You don't look like yourself anymore." Funny thing - the new one does look more like me - my RL self.
There are some forums where I've only had one avatar. There are others where I change them often. There are ones where I have a theme - like I settled into cats here, I had an Enya thing going on another forum.
I still think a contest might be fun. It's something different, and a chance for people to get creative in interpreting themes. One contest I ran earlier this year at TrekBBS was "Women in Space" - avatars could either be female astronauts or astronomers (real, not movie/TV characters). There were some fantastic entries.
My current avatar is very similar to how my Maddy looks: cute little black cat with golden eyes.
