The Great Old Ones are a group of unique, malignant beings of great power in the Lovecraft Universe that once presided over the Earth as gods and rulers.
Cthulhu is a Great Old One who was spawned from an Outer God called Yog-Sothoth.
H.P. Lovecraft quotes[]
"That is not dead which can eternal lie. And with strange aeons even death may die."
and
"When the stars have come right for the Great Old Ones, some force from outside must serve to liberate their bodies. The spells that preserved them intact likewise prevented them from making an initial move."