Major Spoilers Question of the Day: File Not Found Edition

As part of my quest to find as many of the thousands of superheroes created since the 30s, I’ve spent a considerable amount of time this week trying to track down a copy of Funny Pages #36 from 1940, the only appearance of something called the Air Ranger.  I don’t even know if Air Ranger is a superhero (a similar search recently discovered that The Bullet wasn’t a costumed hero but an airplane), but part of me is incredibly frustrated at the constant File Not Found problem.  Of course, I’ve been looking for a Champ Comics #20 (the only appearance of The Green Ghost) since at least 2015, leading to today’s extinct query…

The MS-QOTD (pronounced, as always, “misquoted”) would really hate it if ‘Gilligan’s Island’ disappeared, but I’m also a kid who was raised by a 24-inch Magnavox television, asking: What bit of pop culture, if lost, would be your most tragic “File Not Found”?