What do we call a person who wears animal costumes and stands outside of a restaurant for advertising purposes? They may also represent a team or an organization.
Some might say "mascot." Another might say "in costume." And some might say "desperate."
In certain online subcultures, people who wear animal costumes are (often derogatorily) called "furries". The people I refer to often state that they wish to become or already are an animal, and they dress up as animals in costume. This is very different from, say, mascots, who have nothing to do with this. Mascots are a symbolic representation of something (often an organisation), whereas "furries" are people who are unironically psychologically attached to the costume they wear. The two terms are never interchangeable.