Forest spirits are widely represented in the Udmurt traditional belief system. The present study is aimed at systematising traditional folk beliefs about the best-known mythological beings living in the woods, namely the n’ulesmurt (‘forest man’), palesmurt (lit: ‘half-man’), and obyda (‘forest woman’). The article provides a detailed description of the appearance of forest spirits, analyses their distinctive features and functions, and presents how beliefs about those mythological beings have evolved over the last centuries.