Recommended and mentioned products
aims to provide a fun and easy way to help you find a look for your characters.
The Character Creator is free, and works in a browser. You can save the custom sprite. It's 2D art, though it leans more toward photorealism than a lot of customizable sprites on DLSite or Itchio.
Create your own avatar online
Avatar Maker might be meant for forums. However, it's another online tool for designing shoulders-up portraits.