Calus

Calus is the former emperor of the Cabal, before his eventual overthrow by Ghaul. He is a key-player in the events of Destiny 2, being heard in the Leviathan, Eater of Worlds and Leviathan, Spire of Stars Raid Lairs, as well as in The Menagerie, and the Tribute Hall. He was once a Cabal, but after an encounter with an unknown force (presumably the Darkness), was transformed into something else. His true form is currently unknown.

Reign
Calus rose to power in the Cabal Empire and removed the military aristocracy called the Praetorate from power. His revolution, based in populist roots, gained him the Emperorship. He then moved the capital to the planet of Torobatl to be closer to the people. Calus then appointed his friend Lictor Shayotet, who saved his life during the revolution, to the position of the Emperor's Protector. During his reign, Calus took the wealth of the Praetorate and distributed it among his people. He also granted the Imperial Legions citizenship, created the position of everjoy, which was granted to Moli Imoli, worked to free enslaved Psions, and put down enemy threats such as the Sindu, the Clipse, and the OXA Machine of the Psions. Later on the moon of Brand, a Psion named Otzot rebuilt the OXA Machine. Umun'arath, the Primus of all Legions and the evocate-general of the empire, sent her forces to destroy it. Calus stopped her due to him being impressed by the work of Otzot. Calus then preserved the machine, proclaimed Otzot as Freeborn, held a festival in her honor, and elevated her to his court as "Imperial Dreamer."

Calus was very popular with the people, something problematic for others later; he became friends with many. Among them was Iska'al, a poor merchant who sold Calus teas and spoke about the emperor's troubles with him. Calus did have problems during his rule, however. The Evocate-general Umun'arath was fixated on war, along with his daughter the Princess-Imperial Caiatl.

During his reign, Calus enjoyed the Coliseum. This is where he met Ghaul, an albino who displayed patience, unlike the other fighters, and quickly became his favorite. Calus believed Ghaul's talents were being wasted, and made him Primus of the Red Legion. Calus was worried by Ghaul's relationship with The Consul, but not enough. Behind his back, Ghaul and the Consul were planning to overthrow him with the help of Calus' friends and allies.

Coup and Exile
At midnight, the conspirators: Ghaul, the Consul, Caiatl, Umun'arath, Moli Imoli, Iska'al, Shayotet, and Otzot stormed the palace. Due to Calus' popularity, they couldn't execute him, so they took him and a great number of his supporters and exiled them aboard the Leviathan on a pre-set course.

Calus wallowed in despair for a long time until the Leviathan stopped. It had reached a great void that shorted out its navigational systems. Regaining manual control, Calus believed he was destined to reclaim his empire, and set out to do so. He traveled around the galaxy, visiting strange places, strengthening his resolve to reclaim his empire. Calus also gathered numbers to strengthen his Loyalists, as well as forming an elite group of champions called the Shadows. Calus allied with several alien factions such as the Clipse and the Sindu, although the Sindu initially refused until he annihilated them save for Jarus and another portion of them who agreed to join. Calus sent his Shadows to eliminate his enemies, and among those killed were all of the conspirators, except Ghaul and the Consul. Calus consumed planets to make "royal wine" to hone his psionic abilities. Eventually he arrived in the Solar System and soon sent out invitations to Guardians to board the Leviathan after the death of Ghaul.

Meeting the Guardian
After sending the invitation to his Leviathan to the very same Guardian responsible for killing Ghaul and awakening The Traveler, the Guardian accepted the invitation and completed Calus' various challenges aboard the planet-devouring vessel. Eventually, the Guardian met what turned out to be a robotic copy of Calus, where the two proceeded to do battle (with the robotic Calus assisted by various Loyalists, War Beasts, and Psions). After the Guardian's victory over the robotic copy, Calus offered the Guardian and their fireteam the chance to learn the very same power that he had learned, and to grow "fat from strength", and rewarded the fireteam with various treasures as well. A few months later, the Leviathan had consumed a part of Nessus that contained the Vex Axis Mind Argos, Planetary Core. The Vex mind proceeded to clog the Leviathan and prevent the ship from functioning. In order to fix the ship, Calus enlisted the help of the Guardian he had met previously to defeat Argos and his army of Vex. Shortly after defeating Argos, the shield that protected Argos was removed, threatening to devour the Guardians in the Leviathan. Luckily, Calus saved the fireteam, congratulating them on their victory against the Vex. Even later, current Red Legion Dominus Val Ca'uor launched an invasion of the Leviathan in order to affirm Red Legion control over the Cabal in the Solar System. Once again, Calus enlisted the help of the Guardian and their fireteam to stop the invasion and put an end to Val. Many Loyalists and even a robotic copy of Calus himself were destroyed in the battle. However, the fireteam of Guardians eventually defeated the Dominus with the assistance of Calus and his psionic powers. Calus once again congratulated the fireteam for yet another victory in his favor.

Shadow of Earth
Over a year after the Red War, Calus invited the Guardian to his Loyalist sail barge on Nessus, using Werner 99-40 as a vessel to grant the Guardian the Chalice of Opulence, which will grant the Guardian access to his Mengaerie within the Leviathan, as well as creating a Tribute Hall to honor the Guardian's various accomplishments. Calus, who had grown fascinated with integrating the Hive into his empire, bred Gahlran to wear the Crown of Sorrow, a Hive artifact allowing the wearer to control the Hive around them. This backfired, however, as Gahlran went insane, as the Crown was, in reality, a trap created by Savathun, the Witch Queen in an attempt to control Calus. Gahlran proceeded to infest the bowels of the Leviathan with Hive, attacking any who trespassed; including Loyalists. Wishing to rid his vessel of this Hive infestation, Calus once again asked his favorite Guardian and their fireteam to help rid his ship of Gahlran. After defeating Gahlran and the Hive, Calus named the Guardian the official Shadow of Earth, with his Fireteam and many other Guardians taking the title of Shadow as well. The incident with Gahlran, however, did not deter Calus' attempts to integrate the Hive, as he would proceed to send an invitation to Eris Morn to become the Shadow of the Hive.

Trivia

 * Calus is known to use the term, "O champion mine", a similar phrase to the one used by both the Ahamkara and Worm Gods.
 * It is speculated that this term is used to declare a sort of ownership over the Guardian.
 * Calus is the third known Cabal to speak English in Destiny, followed by The Consul and Ghaul.
 * Calus apparently hates Mara Sov, and thinks she is a fool for trying to prevent the coming Darkness.