Sven Aggesen (also known as Svend Aagesen, Aggessøn, or Aggesøn, in Latin Sveno Aggonis; born around 1140 to 1150, death unknown) was the author of Brevis historia regum Dacie, one of the first attempts to write a coherent history of Denmark covering the period 300AD-1185AD.
The earliest known family member that we know of with some certainty is Sven's great-grandfather, Thrugot, who was married to Thorgunna, daughter of Vagn Aggesøn, a grandson of the legendary Palne Toke.
Notable in the preface of Historia brevis regum Dacie, he mentions that reading the works of Latin historians was something that took up much of his time.
On that note he writes, with sadness, that similar works did not exist for Danish kings, notable persons and events.
The first work we know he wrote is a retelling of Witherlogh (known today in Danish as Lejrloven or Krigerloven or in English as Lejrlaw or Warriorlaw).