Saxo Grammaticus (c. 1150 – 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 first full history of Denmark.
The Jutland Chronicle gives evidence that Saxo was born in Zealand (Danish: Sjælland). It is unlikely he was born before 1150 and it is supposed that his death could have occurred around 1220. His name Saxo was a common name in medieval Denmark. The name Grammaticus ("the learned") was first given to him in the Jutland Chronicle and the Sjælland Chronicle makes reference to Saxo cognomine Longus ("the tall").
He lived in a period of warfare and Danish expansion, led by Archbishop Absalon and the Valdemars. The Danes were also being threatened by the Wends who were making raids across the border and by sea.Valdemar I had also just won a civil war and later Valdemar II led an expedition across the Elbe to invade Holstein.
Sven Aggesen, a Danish nobleman and author of a slightly earlier history of Denmark than Saxo's, describes his contemporary, Saxo, as his contubernalis meaning tent-comrade. This gives evidence that Saxo and Sven might have soldiered in the Hird or royal guard since Sven used the word contubernium in reference to them. There is also a Saxo to be found on a list of clergy at Lund, where there was a Sven recorded as Archdeacon. Likewise there is Dean Saxo who died in 1190, however the date does not match what is known about Saxo.