Father Christmas is "Joulupukki" in Finnish, the word consists of two separate words, "joulu" and "pukki". Joulu means christmas, but is of pagan origin (jul) and pukki means goat, and thus Joulupukki means "christmas goat" (with the exception that it isn't associated with christianity).
The word comes from the time when modern consept of Father Christmas wasn't yet adopted in Finland. These "christmas goats" used to visit houses at Christmas dressed in upside down furcoat and horns in their heads, they caused trouble and demanded booze from people. (I should emphasize that it wasn't a myth, people actually did dress that way and visit houses).
Before that there was similar creature called Nuuttipukki, which came couple days after the christmas on Nuutti's day and took the christmas away.
The word comes from the time when modern consept of Father Christmas wasn't yet adopted in Finland. These "christmas goats" used to visit houses at Christmas dressed in upside down furcoat and horns in their heads, they caused trouble and demanded booze from people. (I should emphasize that it wasn't a myth, people actually did dress that way and visit houses).
Before that there was similar creature called Nuuttipukki, which came couple days after the christmas on Nuutti's day and took the christmas away.