Horus
Horus was an Osiran related to Osiris and Sutekh. By one account, he was the hybrid formed when Osiris' biodata was merged with that of Eliza. (AUDIO: Body Politic) He was also identified as Harpocrates, the God of Silence. (PROSE: Head of State)
Birth
After Osiris was killed by Sutekh, Justine il-Isis searched for the pieces of Osiris' body and, with the help of Anubis and Thoth, attempted to reconstitute him. However, since one vital piece of his biodata was missing, Cousin Eliza of Faction Paradox offered herself as an alternative donor and became the entity known as Horus. (AUDIO: Body Politic)
By another account, Horus was the psi-child produced when Sutekh stranded Osiris in space and Osiris projected part of his mind into the pilot of Isis' search ship. (PROSE: The Sands of Time)
One account related by a Sutekh-possessed Marcus Scarman said that Horus was Sutekh's "brother", just as Marcus was brother to Laurence. (TV: Pyramids of Mars)
Rise and leadership
A tribunal was convened to decide whether Horus or Osiris should inherit the throne. It was judged by Geb, father of Sutekh and Osiris. The tribunal ended when Horus accepted Sutekh's challenge of ritual combat to decide the matter. (AUDIO: Ozymandias)
According to one account, the Fourth Doctor said that Horus and the rest of the Osirans "must have finally cornered [Sutekh] on Earth" following Sutekh's destruction of the Osiran planet Phaester Osiris and his "[leaving] a trail of havoc across half the galaxy". Sarah Jane Smith assumed he meant Egypt, to which the Doctor responded, "The wars of the gods entered into mythology. The whole of Egyptian culture is founded upon the Osiran pattern." He said that Sutekh was defeated by the combined might of 740 Osirans led by Horus. Sarah recognised the name from the 740 gods recorded in the tomb of Thutmose III. (TV: Pyramids of Mars)
According to another account, Horus really led the Osirians to combat Lolita on the Homeworld in a complex time travel-based plan formulated with Cousin Justine. (AUDIO: The Judgment of Sutekh)
By another account, Horus was a cruel dictator who conquered and oppressed more than a hundred inhabited worlds. Wherever he went, he brought plague and famine; he was known to nurture pacifist societies and then unleash vicious killers on them for his own amusement. Following the defeat of Sutekh, Horus placed himself in suspended animation in the Black Pyramid on Beta Osiris; however, the cryogenic systems failed in the 16th century. The Fourth Doctor and Sarah found his corpse in the 2650s. He resembled a cow. (PROSE: Scarab of Death) Contradicting this, Sutekh once claimed that Horus, like the Fourth Doctor, considered all sapient life to be his kith. (TV: Pyramids of Mars)
Worship
He was worshipped by many cultures. The Egyptians of Earth worshiped him amongst the pantheon of gods, many of whom were named after Osirans. (PROSE: GodEngine) The Cult of the Black Pyramid also worshipped Horus and dismissed Sutekh as a false god. (PROSE: Scarab of Death)
The native Martians also worshiped Horus. Forming the Holy Order of Oras, they followed the teachings of the Book of Oras. The Order's teachings were of a non-violent nature and asked its followers to abandon such means. The Ninth Book of Oras was the Rebirth of the Father. (PROSE: GodEngine)
When inducting his earlier self into the Faction, Richard Francis Burton made himself swear by "Horus, the reborn child from whose sacrifice our Faction owes its own rebirth". (PROSE: Head of State)