I've bought the Humble game making Bundle. It seemed a nice way to get some assets so maybe I can make a game for once, because I'm a horrible artist.

There are some resource packs for rpg-maker, and most of them include something called "Battlers". They seem to be static images of characters (mostly monsters), although googling about I have found that there are animated versions, too. They come in two versions: "side" and "front".

There are some examples: https://vxresource.wordpress.com/category/resources/battlers/

I'm curious now, what are them supposed to be used for?

All I can think is ultralow-budget "cinematics", or maybe an old school j-rpg combat system, with the PCs in one side and monster at the other side. The former could be acceptable (IIRC the intro for Legend of Grimrock was made with static images), but the later would be very dull without some attack animations.

Even the original Wasteland and Dragon Wars had some animations in the combat screens! (no attack animations, though)

Oh, that makes sense, I guess. I didn't though of that because the first set of battlers also included portraits for each creature, and they seem more apt as avatars to me.

Any well-known game that uses them?

Thank you very much, that was very illustrative.