Gesta Danorum ("Deeds of the Danes") is a patriotic work of Danish history, by the 12th-century author Saxo Grammaticus ("Saxo the Literate", literally "the Grammarian"). It is the most ambitious literary undertaking of medieval Denmark and is an essential source for the nation's early history. It is also one of the oldest known written documents about the history of Estonia and Latvia.
Consisting of sixteen books written in Latin on the invitation of Archbishop Absalon, Gesta Danorum describes Danish history and to some degree Scandinavian history in general, from prehistory to the late 12th century. In addition, Gesta Danorum offers singular reflections on European affairs in the High Middle Ages from a unique Scandinavian perspective, supplementing what has been handed down by historians from Western and Southern Europe.
The sixteen books, in prose with an occasional excursion into poetry, can be categorized into two parts: Books 1-9, which deal with Norse mythology and semi-legendary Danish history, and Books 10-16, which deal with medieval history. Book 9 ends with Gorm the Old. The last three books (14–16), which describe Danish conquests on the south shore of the Baltic Sea and wars against Slavic peoples (the Northern Crusades), are very valuable for the history of West Slavic tribes (Polabian Slavs, Pomeranians) and Slavic paganism. Book 14 contains a unique description of the temple on the island of Rügen.

Saxo Grammaticus (c. 1160 – c. 1220), also known as Saxo cognomine Longus, was a Danish historian, theologian and author. He is thought to have been a clerk or secretary to Absalon, Archbishop of Lund, the main advisor to Valdemar I of Denmark. He is the author of the Gesta Danorum, the first full history of Denmark, from which the legend of Amleth would come to inspire the story of Hamlet by Shakespeare.

Translated by Oliver Elton.