This Anubis was very different from the Anubis from Egyptian mythology, who was just the Egyptian god of the dead and lacked a good or bad alignment.
When he reveals himself in his incomplete form to Yami Yugi Anubis was shown as a tanned muscular but pulsating man with dirty blonde hair, red eyes, and a jewel embedded to his forehead. His clothing consisted of a black cape attached to spiked padding which were held by strings, along with gray shoulder pads, black pants, and the Pyramid of Light hanging around his neck.
When Yugi had a vision after being driven unconscious by a strange force when looking at the pyramid, he saw Kaiba being grabbed by Anubis who had a black jackal-like head with a white muzzle instead of his human head and his was not pulsating.
After losing the Duel to Yugi, Anubis used the power of the center jewel of the Pyramid of Light to assume a monster form that started off as slime until forming an armored jackal-like monster that could stand on his hind legs, possessed bladed wings, and an axe like blade on top of his head, and the Pyramid's jewel in the center of his chest.
In Egyptian Mythology, Anubis is the Egyptian god of embalming, possessing a jackal head and was said to have created the first Egyptian mummy. Anubis was originally the god of the Underworld and of the dead (later replaced by Osiris). Both of these are similar to character in his title of "Lord of the Dead" and his complete form's jackal-like head, along with his ability to control mummies. However the Egyptians never viewed Anubis as evil, and he was in fact one of their most respected and revered gods due to his role of bringing the dead to the afterlife.
Anubis' powers are connected to the Pyramid of Light, a magical artifact with shadow powers that rival the Millennium Puzzle. With the item, its powers allow him to spiritually travel to any place he wants, transport his mummified body and his item into the Millennium Puzzle's inner world, command undead servants, influence the thoughts of people, and show others a vision of the future. When the Pyramid of Light card is in play in a Duel, Anubis is able to drain life energy from others who have taken damage during the Duel in order to restore himself.
He is also shown to be able to create his cards out of thin air, like the Pyramid of Light card which he put in Pegasus's Deck, and materializing his Sphinx monsters through a black slime that releases from his hands. In his vision of the future, it is revealed that the Pyramid could materialize countless monsters that were his to command for carrying out his purpose of destroying the world, and all life on it.
Anubis's original form shows him with tan skin, a ragged black cape, and the Pyramid of Light. When in his monster form, Anubis is able to breathe a devastating black flame from his mouth and can easily resist other monsters' attacks. In his presence, Duelists can summon Duel Monster cards that have real powers, including their special effects, as Joey Wheeler was able to summon "Gilford the Lightning" and "Gearfried the Iron Knight" to battle Anubis, Maximillion Pegasus was able to summon "Toon Dark Magician Girl" and "Blue-Eyes Toon Dragon" to stop falling debris, while Yugi and Kaiba were able to summon the "Blue-Eyes Shining Dragon", whose special effect to destroy any monster brought his end once and for all.
Anubis was an evil sorcerer who commanded evil Shadow Realm monsters. He and Aknadin created the Pyramid of Light, a failed replica of the Millennium Puzzle. Aknadin sought to have this item given to his son to take over as Pharaoh from Atem, but Anubis stole the evil item. Now, armed with the Pyramid and his monsters at his disposal, Anubis sought to use them to destroy all life on Earth. Pharaoh Atem however stepped up to him and defeated Anubis with the Dagger of Fate. However Anubis sealed his soul inside the Pyramid of Light.
A team of researchers discovered the tomb of Anubis. Yugi solving the puzzle caused both the Pharoah and Anubis to awaken. His awakening caused the tomb to collapse.
Later, another team of scientists uncovered Anubis and the Pyramid of Light. His body and his item as well as other items of his was moved to the Domino City Museum. Anubis's spirit was now free to move about.
One night the sorcerer slips into Pegasus' room at night, placing the "Pyramid of Light" card in with other cards of Pegasus' collection, anticipating Kaiba's plans. Kaiba later defeated Pegasus and took both the "Blue-Eyes Shining Dragon" and the "Pyramid of Light" cards.
Pyramid of Light
Anubis was now able to manipulate Kaiba. Kaiba and Yugi/Atem then Dueled. After Seto played Pyramid of Light a shadow game had begun and made a super-sized Pyramid of Light. To make things worse it removed from play all three of Yugi's Egyptian God cards. Anubis was able to infiltrate the Millennium Puzzle and begun to drain the Pharaoh's life when he lost Life Points. Yugi, Joey and Tristan were sealed in the Puzzle too. Anubis was also able to create a army of undead warriors to guard him in his Resurrection.
Tea was later sucked into the Puzzle. Joey and Tristan got sick of sitting around and eventually started to fight the mummies.
After a while in the Duel, Kaiba tried to destroy the "Pyramid of Light" to gain control of the god cards but Anubis stopped this and took over himself. Anubis Summoned "Andro Sphinx" and "Sphinx Teleia" "Pyramid of Light" He also puts "Theinen the Great Sphinx" face-down on the field. He destroys all of Atem's monsters, but Yugi inside the puzzle stabs an eye inside the puzzle which was the source of the Pyramid of Light's power with the dagger of fate.
Weakened by this, Atem was able to use "Blue-Eyes Shining Dragon" to destroy the pyramid and all of Anubis monsters. However "Theinen the Great Spininx" is revealed and Anubis uses his Pyramid of Light to raise its ATK to 35,000. Atem however brings back the Egyptian Gods and merges them together to destroy "Theinen" and Anubis.
Unfortunately, a part of Anubis' soul was still in the Pyramid of Light and he turned back into his true form. Even with the help of Joey and Pegasus, they were no match for Anubis. However Kaiba found his "Blue-Eyes Shining Dragon" card and gave it to Yugi to seal Anubis. After the dragon was Summoned, it used power of "Shining Nova" to sacrifice itself to seal Anubis and the Pyramid of Light for good.