Ralph Nader is a consumer advocate and political activist who is best known for his role as a consumer watchdog. He is often referred to by his initials, 'NADER', which is the answer to the crossword puzzle clue. Nader has been a vocal critic of corporate power and government corruption since the 1960s, and he has been involved in numerous campaigns to protect the rights of consumers. He is also the founder of several organizations, including Public Citizen, which works to protect the public from corporate abuse.