Mysterious music is something subtle with a hint of suspense, or with a twist of unknown horror. One example is an unfolding revelation in a documentary. Mysterious music tends to be soft and subtle, as if it's hinting towards something suspenseful.
Royalty free mysterious music downloads listed below. Use this background music for videos, youtube, etc...
Suspenseful undercover spy agent music with a subtle tone.
Documentary styled conspiracy music with a suspenseful tone and room for a voice over.
This documentary music is slow, dark, serious and mysterious.
This track is very ominous and sits well be hind a vocal / voice over, or just as general background music which fits without getting in the way.
The Unsolved Mystery is background music for a crime thriller, suspense and noir scene.
Monster music is typically something very horror related and on edge.