List the Tlatoani/Huey Tlatoani of Tenochtitlan, often anglicised as Emperors of the Aztec Empire
The Aztec "Empire" was really an alliance of three allied city states, and all the tributaries and client states that they cowed into paying tribute. So while the rulers of Tenochitlan, the most powerful city state of the three, were the most powerful people in the "Empire," they were not really emperors in the traditional sense
The dates of the rule of each Tlatoani varies depending on the source. I used the dates on the wikipedia list of Tlatoani.
The actual founding of the Triple Alliance dates from the fourth ruler here, the previous were just rulers of Tenochtitlan