Augustus (r. 27 BCE to 14 CE), as the adopted son and heir of Julius Caesar (100-44 BCE), brought an end to the Roman Republic, and on 16 January 27 BCE, by Senatorial decree, he became the first Roman emperor. However, he would not be addressed as a king, but as a princeps, the first citizen.
This is a companion discussion topic for the original content at https://www.worldhistory.org/article/2363/the-principate-of-augustus/.