Digital avatar
A digital avatar is a representation of a denizen of real life which they can use to enter digital media such as the remix world. The only known user of one was Matthew Rockefeller, who used one to appear in the remix world even after having escaped to real life. Their avatar was destroyed after they got run over by an ambulance,[1] rendering them unable to appear in the remix world (and they claimed the same was true of their Stand).[2] However, they later acquired a new avatar with a distinct appearance.[3]
The Scratch users may be considered to be using digital avatars, but more likely are simply representing themselves within projects when they appear. Beyond them, the only other character who interacts with both real life and the remix world is Duolingo Owl, who posts on the Scratch of real life while also being present inside of every remix project they make. It's possible they're in real life and using a digital avatar for their appearances in the remix world, but it's ambiguous. They could just as easily exist in the remix world and somehow be posting on real-life Scratch anyway.