Most people know about the story where Cronus and most of the titans were overthrown by Zeus and his siblings. However, were the Titans simply created to give the Greek pantheon an origin story; or were they actually worshipped before the Olympians came about, necessitating a story for how the titans fell?
More can be said, but not much more than what /u/KiwiHellenist covered in this recent answer on a similar question.