The Black Knight Satellite
A 13,000-year-old alien satellite allegedly parked in polar orbit, watching us. The legend is not one story but a pile of unrelated ones stacked in a trench coat: Tesla's 1899 Colorado Springs claim of rhythmic radio signals, a rumored Gordon Cooper sighting he never actually described that way, assorted Cold War tracking anomalies, and a 1998 photograph from shuttle mission STS-88.
Why it was classified
Nothing was withheld. NASA published the STS-88 frames along with the mission log identifying the object as a thermal insulation blanket that got away from a spacewalking astronaut during ISS assembly — a piece of hardware whose loss is documented, timestamped, and mildly embarrassing.
Why it matters
The Black Knight is the internet's favourite demonstration that a legend does not need a single false claim, only true claims filed in the wrong drawer. Every ingredient is real. The satellite is not.