Netflix's most-watched TV releases in the US are dominated by documentary series like "How to Become a Mob Boss" and true crime and nature docuseries. 2023 has been a standout year for Netflix documentaries with releases exploring themes of personal improvement, anger, and appreciation. Popular Netflix documentary series include "How to Become a Mob Boss," "Escaping Twin Flames," "Life on Our Planet," and "Luna Park Tragedy in Sydney."