Ancient coin depicting the face of Romulus, the first king of Rome. Romulus would have had a co-regent, Tito Tazio
The kings of Rome they may have been 8 and not 7, as we've been told since elementary school, or at least that's what some scholars believe.
Tito Tazio, native to Cures (current Fara in Sabina , Rieti), he reigned for 5 years, making himself the architect of many significant changes within the urban layout of the city.
Why is Tazio never mentioned, then?
Because he almost certainly ruled "only" as co-ruler of Romulus, mythical founder of the city, after the so-called "rape of the Sabine women" .