Like Satan, who was once an angel known as Lucifer, Sauron was originally an angelic being himself called Mairon. As one of the Maiar (the race of immortal spirits from which Gandalf also derives), he ...
Celebrimbor forged all these rings with the help of someone he believes to be named Annatar but is, in fact, Sauron. As we see on The Rings of Power ... likely already popped up on the series.