The entitiy that is angry for no real reason. It's Mad Dummy's role in Undertale.
“Mad Dummy isn't seen very often, as Mettaton hides him. The cause for this is Mad Dummy's...Mad Dummy/MentalTale
“Mad Cre is the UTAUWikiTale role of Mad Dummy. This has been allowed since Mad Dummy is a minor...Mad Dummy/UTAUWikiTale