Grimm's Fairy Tales were originally written in what language?

Originally, Grimm's Fairy Tales were compiled by the Grimm brothers, Jacob and Wilhelm, in "their native tongue" (language) of German. This set of brothers, Jacob (1785–1863) and Wilhelm Grimm (1786–1859), were German academics and authors who specialized in collecting and publishing folklore during the 19th century.

Also, it is a well known fact that the brothers did not actually invent any fairy tales on their own. The stories in Grimm's Fairy Tales existed long before the brothers Grimm were born in Germany in the mid 1780s. The fairy tales that the brothers obtained were part of a rich oral tradition. They were passed down from generation to generation, often by women seeking to pass the time during household chores.

However, as industrialization took root, local traditions changed and academics, like Jacob and Wilhelm, began a quest to save the stories from extinction. They interviewed people. They talked to relatives and friends, collecting whatever tales they could. In 1812, Jacob and Wilhelm published the stories as part of a collection titled Children's and Household Tales. Now, this collection is commonly known in English as Grimm's Fairy Tales.