Short answers, pulled from the story.
Saxo Grammaticus was a Danish historian, theologian, and author born in Zealand around 1150 who likely died around 1220. He is best known as the author of the Gesta Danorum, a sixteen-book heroic history of the Danes and the earliest full account of Danish history.
The Gesta Danorum is a sixteen-book history of the Danes compiled by Saxo Grammaticus, spanning from the legendary founders of the Danish people to around 1187. Its sources included oral tales from Icelanders, letters carved on rocks and stone, ancient volumes, and the spoken recollections of Archbishop Absalon.
Saxo Grammaticus preserved the legend of Amleth inside the Gesta Danorum, a story of a son avenging his murdered father drawn from an oral tradition. The work was first printed early in the sixteenth century by Christiern Pedersen and Jodocus Badius Ascensius, allowing it to circulate through Europe until it reached Shakespeare.
Erasmus praised Saxo's Latin, wondering how "a Dane of that age got so great power of eloquence." R. W. Chambers offered a contrasting view, calling the writing "difficult and bombastic, but always amusing Latin."
The Gesta Danorum is thought to have been started around 1185, and Saxo wrote the preface around 1216. It was first printed early in the sixteenth century by Christiern Pedersen, a Canon of Lund, working with the scholar Jodocus Badius Ascensius.
Modern Danes commonly regard Saxo as their first national historian, but two earlier Danish historical works predate the Gesta Danorum. The Chronicon Roskildense was completed around 1143, and Sven Aggesen's Brevis historia regum Dacie, covering the years 300 through 1185, was probably finished in 1186 or 1187.