The first ruler of the Akkadian empire, which covered most of Mesopotamia by the time he was done, Sargon was also the builder of Babylon (which is probably his most lasting mark on history). Sargon’s reign lasted for 56 years, an impressively long figure by the standards of his era.
In Sargon’s later years, much of the conquered territories rose in rebellion, seeing his old age as weakness. Sargon proved them decisively wrong, restoring his rule with considerable bloodshed and brutality. Sargon’s death led to another round of rebellions, naturally, but the Akkadian Empire lived on for nearly another century.