| The Most Mysterious Song | |
| Type: | song |
| Artist: | an unknown artist |
| Recorded: | 1983–1984 |
| Genre: | |
| Length: | (radio version) |
"The Most Mysterious Song on the Internet" is the nickname given to a cassette recording of an unknown song, most likely created in the mid-1980s.
The song was recorded from a German Norddeutscher Rundfunk (NDR) radio broadcast sometime during the mid-1980s, likely in or after 1984. Since 2019, this song has been the subject of a viral Internet phenomenon, with many users of sites such as Reddit and Discord involved in a collaborative effort to search for the song's origins and artist.
Throughout the search, other unknown songs have been discovered. Users online have coined the term "Lostwave" to describe songs of this nature.