Romuva
The Romuva pantheon was headed by Dievas, the sky god, with Perkūnas the thunder god, tied to the oak, executing his will. Žemyna was the earth goddess, Velnias lord of the dead, and Laima gave out fate.
Lithuania was Europe's last pagan state, and the Teutonic Knights crusaded against it for generations. Mindaugas was baptised in about 1250, but his people did not follow. In 1387 Jogaila, King of Poland, brought baptism to Lithuania proper, and Samogitia was the last region to convert, in 1413.
The old faith faded slowly. In 1547 Martynas Mažvydas's catechism urged readers to give up the cult of Žemėpatis, and fragments survived into the early 1800s.