I get asked to design characters quite often. Here is a selection of them.
It is an interesting process that is sometimes very personal to the client. The characters you like best are often the ones you grew up with. The first characters I designed (professionally, that is) were incidental walk-ons for various Hanna Barbera series back in the 70s. My most sustained effort at creating a consistent world of characters was for the 90s re-boot of Captain Pugwash, where I invented over 30 new characters in the style of the original cartoons in the Eagle comic.
Some of these characters were for animation, others were for books. Most recently one was an AI avatar in an app.