“I am Spartacus” is from a scene in the 1960 movie “Spartacus,” starring Kirk Douglas as Spartacus.
After the army of former Roman slaves led by Spartacus is defeated in battle by legions of the Roman army, a Roman general stands before the captured surviving members of the slave army and demands that they turn over Spartacus, or else all the former slaves will be executed.
Upon hearing this and not wanting his friends to be executed, Spartacus stands up and says “I am Spartacus.”
However, the loyalty of his friends is so great that each of them stands in succession, shouting “I am Spartacus!” until the shouts dissolve into a cacophony of thousands of former slaves each insisting “I am Spartacus!”
Bewildered and still not knowing which of them is Spartacus, but impressed by the loyalty he inspires in his army, the Roman general has all of the slaves crucified in a miles-long display alongside the Appian Way leading back to Rome.
— from the Urban Dictionary
Check out the links below for the movie trailer from 1960 as well as a TV commercial spoof of the famous “I am Spartacus” scene.