Rasputin

Rasputin is the last remaining Warmind, an artificial intelligence built to defend Earth during the Collapse. He is the only Warmind known to have faced The Darkness and survived. He protects something deep below Old Russia that the Fallen House of Devils desire to retrieve. After a mission by a Guardian, he also began connecting to AI that were formerly controlled by other Warminds across the Solar System. He awoke two years after the SIVA Crisis in order to combat the Hive forces of Xol and Nokris.

Events of Destiny
In Siege of the Warmind, Rasputin comes under attack by the Hive and a Guardian is tasked with defending him.

In the Strike Fallen S.A.B.E.R., a fireteam attempts to prevent the Fallen Shank S.A.B.E.R.-2 from accessing Rasputin's network and using his array of Warsats to attack the City.

In The Buried City, The Ghost mentions that "He's everywhere now." at the end of the mission while analyzing a machine.

SIVA Crisis
After the Fallen House of Devils reactivated SIVA, Lord Saladin hinted that the Vanguard didn't know Rasputin's true intentions, revealing that Rasputin had attempted to prevent the Iron Lords from reactivating SIVA, killing around 100 Iron Lords, trying to prevent them from releasing the evil.

Events of Warmind
Rasputin, along with Nokris and Xol awakened a few months after the Red War. Xol launched an assault on the Warmind, but failed in his attempt. Rasputin, along with The Guardian, with assistance from Ana Bray, defeated Xol using an upgraded version of the Valkyrie. When Xol was defeated, Rasputin granted an audience to The Guardian, Bray, and Zavala. There, he declared that he would indeed protect humanity, but on his own terms as he deploys Warsats throughout the system.

Events of Season of the Worthy
Near the end of the Season of Dawn, Osiris is seen confronting Rasputin, asking which side he is on. In Season of the Worthy, Ana Bray insists that Rasputin could help destroy The Almighty before it crashes into the Last City, with Zavala reluctantly agreeing to work with him. In the Warmind Bunker inside Io, it is revealed to the Guardian and Zavala that Rasputin had his attention to the Pyramid ships in the outer rims of the Solar System slowly approaching the Earth and the Traveler. Right after, Rasputin shows through Zavala's Ghost the emergency broadcasts that were made during the Collapse, showing that he has been silent for so long because he would fail his duties again, and have to go through another Collapse.

Events of Season of Arrivals
Eventually, when a Pyramid approached Io, Rasputin opened fire on it but fails to destroy it and is disabled in the process. Ana later recovers a fragment of Rasputin before evacuating to the Last City.