Just because I hear there was some uncertainty on this point...
the first Emperor of Rome was Augustus (the dictator formerly known as Octavian).
If Julius Caesar had been officially made master of Rome, he would technically have been a king. "Emperor" is a miltary term-- "imperator" in Latin-- which Augustus appropriated to make his rule more authentic, since in the Republican constitution a miltary leader might be given control of Rome in emergencies. That way, the senate was still officially the main body of government.
Smart guy, that Octy.
Btw, mad props to Tooley for getting me from the airport. I wish I had a peppermint rose for you.