A powerful Goa'uld System Lord. Historically, he probably posed as a Greek god on Earth, one of twelve Titans who ascended to supreme domination. According to Earth mythology, Cronus became father to Zeus, Hera, Poseidon and Hades (which may indicate that Cronus is the father of Sokar, a powerful Goa'uld whom he and the System Lords banished).
Cronus is the most influential of the System Lords, and was sent to Earth as one of three System Lord representatives to negotiate a non-aggression treaty with the humans (moderated by the Asgard). After his fellow System Lord Nirrti tried to kill him, his life was saved with a Goa'uld healing device by Samantha Carter.
Cronus is the sworn enemy of Apophis, a fallen Goa'uld System Lord. Teal'c's father was once First Prime of Cronus, but was unjustly executed for failing to win an unwinnable battle. For this reason, Teal'c vowed as a child to one day become First Prime of Apophis. With help from an android duplicate of himself, Teal'c eventually succeeded in killing Cronus when the System Lord moved to seize control of the planet Juna.
Fair Game - Cronus joins Nirrti and Yu in visiting Earth to negotiate for its inclusion in the Asgard Protected Planets Treaty, but is attacked and nearly killed by Nirrti. Carter saves his life.
Crossroads - Teal'c has a vision of his father's death, when Cronus murdered him by crushing his larval symbiote.
Double Jeopardy - Cronus captures SG-1's robot doubles, but a daring assault on his mothership allows Teal'c and his double to kill him and win their revenge.
Stargate: Continuum - In an altered timeline, Cronus is still alive and in the service of Baal, who has used his knowledge of the future to become the most powerful of the System Lords.