Water spirits or goddesses can be found in numerous mythologies around the world. They are usually the protector of their own particular spring, river, or body of water. Depending on the mythology they can be shy and secretive, or very dangerous, and are almost always captivating and seductive. In Japanese folklore, a Kappa is a type of water sprite, and in ancient Greek mythology Naiads are nymphs attached to rivers, springs, fountains and wells. The Neck, or Nixie, is a Germanic and English water spirit that loves music and will lure humans deep into their waters to drown. A similar creature is the Slavic Rusalka. In Wales, water spirits called Morgens will drown men, and in Scotland the Kelpie might lure children to their death. The Scandinavian Huldra might be kind to those who show her respect, but can also be ruthless and severe. Most water spirits take the form of beautiful young women with long flowing hair, and many, such as the Kelpie and Nixie, can shapeshift into other forms.
If Goldberry is a river spirit, then she seems to be of the benevolent kind, and possesses additional powers that allow her to control the weather (Tom mentions that it is raining outside because it’s Goldberry’s ‘washing day’).
The belief that spirits inhabit animals, plants and natural features is called animism, and is important to many religions and cultures, such as Shinto and Shamanism. Nature worship in general can be found all over the world.