What noun means "an unabashed, incorrigible person"?

Let’s say I know a person that unabashedly engages in behavior that is seen as undesirable (but not necessarily immoral or eccentric; for example, someone that is very brazenly nerdy). I am specifically focused on this person exhibiting such behavior without embarrassment or regard for others’ opinions, i.e. someone that is not afraid to stand out. Is there a word (noun) for such a person, preferably one without strong negative connotations?

Some words I think don’t quite work:

• "Nerd" (and e.g. "geek", "dork", etc.) suggests a specific behavior/trait that isn’t correct for my usage, and doesn’t usually suggest brazenness.
• "Reprobate" has strong overtones of immorality. "Libertine" similarly has negative connotations.
• "Rebel", "renegade" and "maverick" all suggest that the person is actively violating rules, which isn’t necessarily the case (and, again, are often seen as negative).