Nightwolf made his first appearance in Mortal Kombat 3. He is the only Native American character in the Mortal Kombat series. He is described as a historian and shaman, and although he prefers a life of solitude, his tribal lands provided a safe shelter for Earthrealm's warriors during Shao Kahn's invasion.
Before the events of Mortal Kombat 3, Nightwolf had received a vision from Raiden warning of the impending invasion of Earthrealm by Shao Kahn. Through shamanic magic, he was able to shield his tribal lands from Kahn's extermination squads and provide protection for Earthrealm's other chosen warriors. Once they were all assembled, they set out on a mission to defeat Shao Kahn and his minions, emerging victorious in the end.
After Mortal Kombat 3, Nightwolf returned to his preferred life of solitude. He didn't resurface until the events leading up to Mortal Kombat: Deception. He began having visions of Onaga, the Dragon King, returning to power. Realizing the impending doom Onaga would bring, Nightwolf knew what he must do. He needed to trap Onaga in the Netherrealm, thus insuring he could never return to power.
In order to do so, Nightwolf would need to taint his soul so he could enter the Netherrealm. He employed an unusual method passed down to him by his ancestors called the "Sin Eater". By doing this, he absorbed the sins of his ancestors, successfully tainting his soul. Once in the Netherrealm, he drew a binding symbol on the ground and chanted the ancient words that would draw the spirit of the Onaga to the Netherrealm. Once Onaga appeared, Nightwolf released the sins of his people into the mystic symbol, and their weight bound Onaga to the Netherrealm. Free of the corruption he had harbored, he was expelled from the Netherrealm.
After his spirit guides led him back to Earthrealm, it wasn't long before he began to have visions, once again. This time it was of a great battle, where an unknown power was forcing the participants to fight each other. After speaking to Johnny Cage, Nightwolf realizes his visions were of the events leading to Mortal Kombat: Armageddon, and he agreed once again to aid in a battle against Shinnok and his forces.
Eventually, Nightwolf was met by Kitana and the spirit of Liu Kang. Due to their bond in life, Kitana was able to keep Liu Kang's spirit with her. However, through magic, Nightwolf relieved Kitana of her burden and took on the responsibility of looking after Kang's spirit until a way was found to reunite him with his body.
Real Name:
Real Name: Grey Cloud
Alignment:
Alignment: Good
Mortal Kombat 3

Nightwolf works as a historian and preserver of his peoples culture. When Kahn's portal opens over North America, Nightwolf uses the magic of his Shamen to protect his tribes sacred land. This area becomes a vital threat to Kahn's occupation of Earth.
Mortal Kombat: Deception

As the Shaman of my tribe, my connection with the supernatural has been interrupted by visions of dark presence. To confront this foe, I have assumed the role of Sin-Eater to absorb the sins of my tribesmen. I must embrace this corruption, though I will eventually become a threat to those I care for. It is a necessary evil if I am to save the realms.
The Sin-Eater ritual has corrupted my soul and will therefore allow me to enter the Netherrealm. There I will implement my plan to defeat Onaga. The sins I have absorbed have poisoned my temperament, however, and I have forced myself into exile until my task is complete in the depths of Hell.
Mortal Kombat: Armageddon

After imprisoning Onaga's corrupt soul, I was released from the Netherrealm. I passed through the spirit world before emerging in Earthrealm, surrounded by a pack of wolves, my spirit guides. I had only faint memories of that brief journey... or did it last an eternity?
The Ancients spoke to me of a coming storm that would pit the warriors of the realms against each other in an epic battle. But most disturbing of all was a warning that a hidden evil was manipulating these warriors, forcing them to participate.
My visions were seemingly made real when, at a gathering of the Forces of Light, Johnny Cage revealed that Shinnok had returned, and that the fallen Elder God was assembling the Forces of Darkness once more. I agreed to help Johnny Cage and join his fight.
At the summit, Kitana approached me. I was amazed to find that she was accompanied by the spirit of Liu Kang. The bond between them was strong; thus she was able to keep his energies intact until a way to reunite his body and soul could be found. There was not much I could do to help until I achieved a much higher level of shamanic power. I transferred the bond from Kitana to myself and accepted my role as Liu Kang's new spiritual anchor. Perhaps this unknown power sought by the Forces of Darkness could be the key to helping Liu Kang find peace.
Mortal Kombat (2011)

Nightwolf is one of few Earthrealm mortals with a strong connection to the spirit world. A powerful Native American shaman, he is guided by the empyrean forces and communes with divine beings such as Haokah, known to the East as Raiden. Nightwolf's devotion allows the Spirits to work through him, granting him unnatural long life and ethereal weapons to kombat the darkness that threatens mortalkind. In the coming crisis, however, it is not Nightwolf's arsenal that will alter fate. His faith in the Spirits will inspire those who have lost hope.
Mortal Kombat 11

Every generation, the Great Spirit chooses a worthy warrior to become Nightwolf: the Matoka's champion and protector. Grey Cloud proved worthy when he laid down his life to prevent the Black Dragon from plundering what remained of his tribe's sacred artifacts. As Nightwolf, Grey Cloud possesses extraordinary magic granted by the Great Spirit. He uses it not only to fight for the Matoka's future, but also to defend all of Earthrealm.
Mortal Kombat 3

Nightwolf helps other Earth warriors escape to his sacred land. Once there they regroup and form a plan of attack against Shao Kahn's invasion. Nightwolf has trained hard for this battle. Finally he faces Shao Kahn and emerges victorious.
When the Earth returns to its normal state, Nightwolf peacefully regains the lands his Native-American people lost over many years. They establish their own proud nation and soon become the great leaders of Earth.
Mortal Kombat: Deception

Nightwolf had traversed realms and fought many demons to get to this place deep within the Netherrealm. Using knowledge passed to him form his forefathers, he drew a binding symbol on the ground and chanted the ancient words that would draw the spirit of the Dragon Kong to this wicked place.
Nightwolf had carried the burden long enough. He released the sins of his people into the mystic symbol, and their weight bound Onaga to the Netherrealm. Free of the corruption he had harbored for so long. Nightwolf was expelled from the depts of the Netherrealm and into the unknown.
Mortal Kombat: Armageddon

The power Nightwolf received from Blaze carried him to the spirit world, an existence between realms from which shamanic power originates. He became a living ghost ? the ultimate shaman! Nightwolf found his ally Liu Kang lost in the spirit energy and guided him back to the physical world. Nightwolf then reunited Liu Kang with his body.
Mortal Kombat (2011)

It took all of Nightwolf's power to destroy Shao Kahn. His spirit guide, the wolf, had aided him in the battle, but in the aftermath its presence was no longer felt. Nightwolf returned to his home, seeking the elders' help in reconnecting to the spirit world. During their ritual, his wolf returned to him - changed. Shao Kahn had tethered his soul to the wolf spirit in order to cheat death. Now corrupted with Shao Kahn's evil, Nightwolf has transformed into his Animality, his bite converting his victims into subservient lycanthropes. Through Nightwolf, Shao Kahn will conquer Earthrealm one mortal at a time.