Väki is a supernatural power in Finnish mythology. It was believed by Baltic Finns that väki resided in natural sites, objects, and animals. Väki has been compared to mana. However, according to Laura Stark, väki is about an impersonal power rather than a universal force. Väki has also been compared to orenda.

Some folklorists have stated väki are in objects, especially ones connected to the world of the supernatural. The concept of väki was first documented in the 18th century by Christfrid Ganander in his book Mythologia Fennica.

According to Kaarle Krohn, väki originated from animistic beliefs. There is a lack of information regarding how most kinds of väki were used by tietäjä.

The word väki is polysemic with two interrelated meanings: a) strength or power, and b) a troop. In modern Finnish, väki means a crowd of people or inhabitants of a home or location. The word could also be translated to mean folk or people. The word väki also has a meaning of "strength, power", although in modern usage it mainly occurs as a modifier as in väkiviina "strong liquor". The term refers to both physical and magical power. The term väki is also used for a haltija or a group of them. This article discusses the meaning "magical or supernatural power".