wild man

Short definition from Wiktionary

Noun

1. 1
   A primitive man who dwells outside of civilized society; a savage person without culture.
2. 2
   A rowdy, dissolute, rash, or violent man.
3. 3
   A man who advocates unorthodox or outrageous opinions or who behaves in an eccentric manner.
4. 4
   Alternative form of wild man.