Abstract. − This article analyses the evil qualities in spiritual beings which are venerated by the Bulsa and Koma of northern Ghana. In particular the mongoose, in both its animal shape and as a spiritual being, is regarded as malignant and harmful. Surprisingly, the Bulsa mongoose is associated and sometimes even equated with a particular ancestress, namely the shrine owner’s mother’s mother. In addition, war and bloodshed are often strongly associated with the mongoose shrine. Among the Nankana, it can only be acquired by men who have killed another human being. These widely differing meanings and functions can perhaps be ascribed to the deep fear of a powerful and malicious supernatural being and by the desire to overcome this fear through ritual activities. [Northern Ghana, Bulsa, Koma, rituals of the mongoose, matrilineality, evil]