Who declared, "I came, I saw, I conquered"?

I came, I saw, I conquered is an English translation of the Latin veni, vidi, vici. According to ancient Roman historian Suetonius’s Lives of the Caesars, Julius Caesar used the phrase veni, vidi, vici during a Roman triumph in 46 B.C. that followed a successful military company. Caesar, a famous military general, used the phrase to emphasize the swiftness of his victory. The phrase implies that Caesar conquered an area immediately after seeing it for the first time.

Source: Dictionary.com