They Called Him Mostly Harmless
- Documentary
- Year: 2024
- Channel: Investigation Discovery
- Channel: Anchor Entertainment
- Genre: documentary, crime, mystery
- Country: USA
- Duration: 86 min
When an unidentified hiker is found deceased in the Florida wilderness, authorities release a sketch. Multiple hikers call in claiming to have met the man. There's only one problem – he never told them his name. It would take two years, thousands of devoted internet sleuths, and a miracle of science to identify him, and that's when the trouble really starts.