Digital avatar
A digital avatar is a representation of a denizen of real life which they can use to enter the world of 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,[1] rendering them unable to appear in the remix world, and they claimed the same was true of their Stand,[2] but they later got a new one with a distinct appearance.[3]
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.