In Finnish mythology, a hiisi is a spirit or supernatural being often associated with nature and the wilderness. Traditionally, hiisi were believed to inhabit forests, hills, and other natural landscapes, sometimes acting as guardians of these areas. They are often depicted as mischievous or malevolent, causing trouble for humans who venture too close to their domains. Hiisi can also refer to a specific type of forest spirit that is linked to ancient Finnish pagan beliefs. Over time, the concept of hiisi has evolved, and in modern usage, it can denote a variety of supernatural entities, reflecting the rich tapestry of Finnish folklore and its connection to the natural world.