Once a powerful Goa'uld System Lord, Anubis was banished by the others because his actions were deemed unspeakable, even among the Goa'uld. He was believed destroyed, but managed to escape and learn the secrets of ascension. But the Ancients did not want the Goa'uld to join them on a higher plane of existence, and tried to force him to descend. They were only partially successful, and Anubis became trapped between the two planes of existence -- now a powerful adversary for the Tau'ri and the Goa'uld alike.
Because of his knowledge of the Ancients, Anubis amassed unimaginable advanced technologies, gathering strength for hundreds of years before returning to take his revenge upon the System Lords and dominate the galaxy. With weapons and armies to rival the entire collective power of the System Lords, he posed the largest threat to ever enter their collective domain, as well as to hundreds of peaceful worlds that stood in the shadow of his destructive hand.
Biologically speaking Anubis existed as a form of incorporeal energy, and wore a mask to keep his form intact. It appeared not entirely unlike the liquid-like event horizon of the Stargate, akin to the Ancient's technology.
Anubis was responsible for single-handedly destroying an entire fleet of System Lord motherships with the combined powers of the Eyes, as well as annihilating the planet Abydos. Using the technology of the Ancient's healing device, he also engineered an army of nearly unstoppable Kull warriors.Stargate Command, where he managed to escape through the Stargate in the body of Russian officer Alexi Vaselov -- but he found himself frozen near the gate on an ice-covered planet, trapped.
It is not known how he escaped the frozen world but, as the war against the Replicators intensified, Baal revealed to the S.G.C. that Anubis had returned and planned to use the Ancient weapon on Dakara to eliminate all life in the Milky Way Galaxy.Daniel Jackson was killed by Replicator Carter and ascended by Oma Desala, he encountered Anubis on a higher plane. Anubis disguised himself as "Jim", a patron to the Astral diner.
Jim maintained a friendly rapport with Daniel in order to goad him into learning that Oma was responsible for Anubis's ascension in the first place. When Anubis removed the guise of Jim and revealed his true nature, Jackson's call to action spurred Oma to engage Anubis in eternal combat -- preventing him from ever threatening anyone again.
Between Two Fires - Anubis (not appearing himself) sends his envoy, Tanith, to offer an ultimatum to the Tollan curia: destroy Earth or face the wrath of an unseen Goa'uld.
Summit - Anubis (not appearing himself) sends Osiris to represent him at the System Lords' summit. He also sends Zipacna to wipe out the Tok'ra.
Fail Safe - Keeping his promise to destroy Earth, Anubis (not appearing himself) sends a naquadah-enriched asteroid in the path of Earth.
Revelations - Anubis uses advanced technology to probe Thor's mind, in hopes of learning the powerful secrets of the Asgard.
Redemption, Part 1 - Using Asgard holographic technology stolen from Thor's mind, Anubis appears at the SGC to declare Earth's doom, using a weapon of the Ancients to turn the Stargate into a doomsday weapon.
Full Circle - The System Lords now against him, Anubis harnesses the final Eye to his command, wiping out an entire fleet of their motherships before turning the weapon on the peaceful world of Abydos.
Fallen - Eager to learn the secrets possessed by Jonas Quinn, Anubis implants a mind probe into his brain.
Homecoming - Anubis attacks Langara and occupies the capital of Kelowna in search of naquadria, but his mothership falls under attack by the combined efforts of the System Lords. His initial naquadria research a failure, Anubis flees in an escape pod.
Evolution, Part 1 - Anubis sends his super-soldiers after the Goa'uld Ramius and Tilgath, with the intention of absorbing their armies.
Evolution, Part 2 - The team learns that Anubis has created an entire army of Kull warriors, but temporarily disable his ability to create more.
Lost City, Part 1 - Anubis punishes his Jaffa warriors for failing to stop SG-1 on P3X-439, commanding his super-soldiers to kill them.
Lost City, Part 2 - Anubis brings an invasion fleet to Earth and attempts to dissuade the President of the United States from resisting. His ship is later destroyed, and Anubis is presumed dead.
Lockdown - A strange illness in the S.G.C. turns out to be Anubis attempting to access the Stargate.
Reckoning, Part 1 - Baal reveals that Anubis is, once again, in charge.
Threads - Anubis moves to capture an Ancient super-weapon on the planet Dakara, planning to wipe out all life in the galaxy and reshape it as he wishes.