Forget the Hollywood movie with Will Smith. In real UFO folklore, the Men in Black (MIB) are deeply sinister and disturbing figures, closer to psychological horror than action. They appeared on the scene in the 1950s, linked to the case of Albert K. Bender, a UFO researcher who abruptly closed his organization after receiving a visit from three men in black suits.
The MIB are almost always described in the same way: men dressed in impeccable but outdated black suits, fedora hats, sunglasses, and driving old model black cars (such as Cadillacs or Lincolns) that seem new, and even smell new. But it's their behavior that's terrifying. They act as if they're 'disguised' as humans. Their skin is sometimes described as too pale or plastic, their movements are stiff, and their way of speaking is mechanical or anachronistic. Often, they don't understand basic customs, such as using a pen, drinking water, or eating.
They visit UFO sighting witnesses or investigators, presenting themselves as government agents (CIA, Air Force), but their credentials don't exist. Their message is always a veiled threat: 'Stop investigating. Forget what you saw. If you talk, there will be consequences.' It's insinuated that they're not human agents, but cyborgs, disguised aliens, or demonic entities in charge of maintaining the veil of ignorance. The Men in Black personify modern paranoia, the fear of the 'Deep State,' and the feeling that there's a hidden reality that we're prohibited from knowing. They're the guardians of the secret, in charge of erasing the truth and silencing those who dare to look too long at the sky.