A "Sigma male" is a term used in the social hierarchy for a popular, successful, but highly independent and self-reliant man. He is considered to be a lone wolf.
This book might help you figure out who you are at your core:
If you consider yourself to be self-sufficient. Self-reliant You appear to be on the periphery of the hierarchy. Take pleasure in being alone. And you prefer to think things through before acting.
The Sigma Male is introverted and avoids mainstream culture, but he excels in life, is well-liked by women, and enjoys success.