Ferengest

The Ferengest is a supernatural being in Ferengi mythology, similar to that of a ghost.

Ferengi folklore holds that if a Ferengi violates the customs or ethics of their society, they will be haunted by a Ferengest of an ancestor. In 2370, both Quark and Nog believed that a Dhrakellian inhabiting Deep Space 9 was a Ferengest.