MIB stands for "Men in Black," which is an alien film franchise. The franchise includes several movies that revolve around a secret government agency responsible for monitoring and regulating extraterrestrial activity on Earth. The agents of the agency are known as "Men in Black."
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: Alien film franchise, for short. Explanations are generated by AI and may be inaccurate.