Kalanpäinen is Great Old One who currently resides in the areas of Finland. Dagon was compared to Kalanpäinen by Cronelius.
Kalanpäinen was an Great Old One, who ruled over the are of Finland, until he, alongside Iku-Turso and the other Old Ones, were sung into the swamps by Finnish sages and poets, who had learned these abilities from the Sámi people. Only myths and some of the Deep Ones remained in the country.
Around the 1930's author Matts W. Cornelius, who was a correspondent of H. P. Lovecraft, wrote stories in which he compared Kalanpäinen with the Great Old One Dagon.
The Deep Ones, especially those who live in Lauttasaari, still seek to awaken the Kalanpäinen and the Old Ones, so that they could reclaim the world.
- Kalanpäinen means "fish-head" or "fish-headed" in Finnish .