I was looking at the synopsis for The Brother from Another Planet (1984), and part of the plot involved Men in Black trying to track down the titular Brother.
I wondered, what was the first depiction of Men in Black in television or cinema?
I don't mean G-men that were simply some Federal Agent, like dapper FBI agents fighting the mafia. Rather I mean those mysterious men, dressed like government agents, who tried to track down witnesses of something the government was trying to cover up, such as supernatural or extraterrestrial activity-- like Will Smith's and Tommy Lee Jones' characters in Men in Black.