The Osirans were an ancient and incredibly powerful but now extinct race. The renegade Sutekh was a crazed super-being who feared that all forms of life might, one day, challenge his hegemony and so became Sutekh the Destroyer, the destroyer of all living things. This included his home planet Phaester Osiris and ancient Mars.

Sutekh's brother Horus and the remaining 740 Osirans tracked Sutekh down to Ancient Egypt and used their powers to restrain and imprison him in a pyramid on the planet Earth. He was placed in a remote location with the Eye of Horus beaming a signal from Mars to suppress Sutekh's powers and hold him an immovable prisoner. The tales of the Osirans were remembered in Egyptian mythology; Sutekh as the god Set, brother of Horus; and in the designations Sados and Satan.

He took possesion of The Doctor's body and force himself free, promptly releasing The Doctor from his power. The Doctor was eventually able to defeat the freed Sutekh by trapping him in a time tunnel for thousands of years; longer even than the extended life span of an Osiran.