Ukko

Ukko (Finnish: [ˈukːo]), is a thunder and weather god in Finnish mythology, whose vital role is fertilizing fields with his thunder and rain.

Unto Salo believes that Ilmari, the Finnic sky god, is the origin of Ukko, but that as Ukko Ilmari experienced very significant, although far from total, influence from the Indo-European sky god especially in the form of Thor. Eemil Nestor Setälä also stated that Ukko can't be a very old name for a god and that the thunder god cult among Finns was of Germanic origin. According to Martti Haavio, the name Ukko was sometimes used as a common noun or generalised epithet for multiple deities instead of denoting a specific god. In 1789, Christfried Ganander wrote that the forest god Tapio was sometimes honoured with the name Ukko.

Ukko is parallel to Uku in Estonian mythology, but it is highly debated if such god was ever worshipped in Estonia. According to the Etymological Dictionary of the Finnish Language, the word was loaned into Estonian from Finnish and the first to use it in the sense of a high god was Friedrich Reinhold Kreutzwald in the 1830s. Kaarle Krohn believed Kreutzwald had confused the Finnish Ukon vakka and Ingrian Ukko vak, a sacrifice to Ukko, with the Estonian Tõnni vak, a sacrifice to the household spirit. There has also been a mention of sacrificial stones in Estonia called Ukko's stones. According to Oskar Loorits, Kreutzwald had copied "high god Uku" from Finnish Christfried Ganander, but the Ukko cult had many Scandinavian features which had also spread to the coasts of Virumaa, Estonia.