Cult of Osiris
Osiris is a famed Warlock, seen both as notorious and acclaimed for what he has done. He lead the Tower in numerous instances in strikes against the Vex and other forces of Darkness.
Osiris was once apprenticed to the Speaker. He is known for his exile because of his research into the Darkness and the Vex. He served as the Mentor to Ikora Rey. It is said that he has achieved a state of permanent radiance, possibly both as a Dawnblade and as a Sunsinger.
Osiris, however, questioned the need for the continuous attacks and strikes. He did not seek to ally, but he did desire to experiment and explore their abilities.
He, along with Saint-14 were crucial to the City's Defense at the Battle of Six Fronts. There, it was said that Osiris was appearing at numerous places all along the battle. Some of the participants even reported that he was appearing at different places at the same time.
It has been revealed that Osiris has been within the Vex network for an extended period of time.
He was the inspiration/founder for the Cult of Osiris found in Destiny.