Sargon was the first person in recorded history to create an empire, or multi-ethnic state. His empire encompassed the region of the Tigris and Euphrates rivers, and part of what is present-day Turkey.
Sargon of Akkad was probably the same person as the first Sargon of Assyria (also known as Sharrukin or Sharru-kin). Sargon's empire would presumably have included Assyria. He is listed in the Assyrian king list as the son of Ikunum and the founder of a dynasty.
The Sumerian "Sargon legend" gives Sargon's father as La'ibum. It describes how Sargon became the cupbearer of Ur-Zababa, the king of Kish in Sumer. Sargon has a dream in which he is favoured by the goddess Inanna, who drowns Ur-Zababa in a river of blood. He tells Ur-Zababa about the dream; Ur-Zababa tries to have Sargon eliminated, but Inanna prevents it. Ur-Zababa sends Sargon to king Lugal-zage-si of Uruk with a message on a clay tablet about murdering Sargon. However envelopes had not yet been invented (the legend appears to be lost at this point, presumably it describes how Sargon becomes king).
From the Sumerian king list: "in Agade, Sargon, whose father was a gardener, the cupbearer of Ur-Zababa, became king, the king of Agade, who built Agade; he ruled for 56 years." Confusingly, Ur-Zababa and Lugal-zage-si are both listed as kings, but several generations apart - perhaps Ur-Zababa is supposed to have lived on in the palace of Kish long after losing the kingship of Sumer. Sargon is the successor to Lugal-zage-si and is the founder of a new dynasty: his son is Rimuc.
His daughter was Enheduanna, the author of several Akkadian hymns.
There is another legend of Sargon, perhaps Assyrian.
See also: Akkadian Empire, Enheduanna, Sargon II of Assyria
The Sargon legend: translation - http://www-etcsl.orient.ox.ac.uk/section2/tr214.htm - Black, J.A., Cunningham, G., Fluckiger-Hawker, E, Robson, E., and Zólyomi, G., The Electronic Text Corpus of Sumerian Literature (http://www-etcsl.orient.ox.ac.uk/),
The Sargon legend: translation - http://www-etcsl.orient.ox.ac.uk/section2/tr214.htm - Black, J.A., Cunningham, G., Fluckiger-Hawker, E, Robson, E., and Zólyomi, G., The Electronic Text Corpus of Sumerian Literature (http://www-etcsl.orient.ox.ac.uk/),Oxford 1998- .