Apophis is the rival of Ra; he is the Serpent God who rules the night. Teal'c was serving him until he realized that the Goa'uld were actually no gods.

The first appearance of Apophis in the series is also the first off-world activation of the SGC Stargate since the mission on Abydos. He kidnapped a US Air Force officer and his Jaffa killed four others. He was then looking for hosts for his queen and their children.

Among his doings, we can notice his hunt of the the Fenri, in order to get its invisibility ability. it is during one of these hunts that he discovered the existence of the Nox.

Apophis tried several times to destroy Earth. He first attacked it with two Ha'tak, but SG-1 and Bra'tac destroyed them from the inside. Apophis escaped with his son Klorel thanks to the onboard Stargate, but he lost many Jaffa. He also lost his position of System Lord.

That is why he tried to take revenge, using Teal'c's son, Rya'c, who was brainwashed by using Nish'ta. He sent him onto Earth so that he would spread a mortal virus that would have killed every living thing on Earth within a week. Fortunately, SG-1 discovered that virus and prevented it to be widespread.

Later, Apophis was captured by Sokar and sent to Netu. He hid there in an armour with a mask, and took the name of Na'onak. He became First Prime of Bynarr, and then killed him to take his place. His final aim was to be appointed leader of the Underworld: when he should kiss Sokar's seal, he would stab him.

Though it went wrong, Sokar died and Apophis took control of his armies.