Obake (お化け) and bakemono (化け物) (sometimes obakemono) are a class of yokai, preternatural creatures in Japanese folklore. Literally, the terms mean a thing that changes, referring to a state of transformation or shapeshifting.
These words are often translated as ghost, but primarily they refer to living things or supernatural beings who have taken on a temporary transformation, and these bakemono are distinct from the spirits of the dead. However, as a secondary usage, the term obake can be a synonym for yūrei, the ghost of a deceased human being.
A bakemono’s true form may be an animal such as a fox (kitsune), a raccoon dog (tanuki), a badger (mujina), a transforming cat (bakeneko), the spirit of a plant — such as a kodama, or an inanimate object which may possess a soul in Shinto and other animistic traditions. Obake derived from household objects are often called tsukumogami.
A bakemono usually either disguises itself as a human or appears in a strange or terrifying form such as a hitotsume-kozō, an ōnyūdō, or a noppera-bō. In common usage, any bizarre apparition can be referred to as a bakemono or an obake whether or not it is believed to have some other form, making the terms roughly synonymous with yokai.