KALEO are an Icelandic rock band led by JJ Julius Son, and their international breakthrough came with a smoky, gospel-tinged blues number. "Way Down We Go", released in 2015 and a hit through 2016, became a fixture of film and television soundtracks, its brooding hook turning up everywhere from medical dramas to trailers.
The band have a real catalogue and a strong live reputation, and songs like "All the Pretty Girls" have found audiences. But that one bluesy single has pulled clearly ahead of everything else.
On streaming, "Way Down We Go" sits near 1.6 billion plays, while their next most-streamed track trails at around 310 million. That puts the ratio at about 5.13, just over our 5.0 threshold.
By our measure KALEO are a certified one-hit wonder, though theirs is a borderline call. They are a working band with more than one song their fans love, and a single strong release could nudge them back under the line. Its endless use in films and trailers has only widened the gap. For now, one sync-friendly blues hit carries the catalogue.