Amahl Farouk or the "Shadow King" is an ancient and powerful mutant and psychic parasite that possesses the bodies of those with great power.
Little is known of the Shadow King's origins other than his true name being Amahl Farouk and that he is a malevolent psychic parasite that was the enemy of another psychic mutant that battled him in the Astral Plane and defeated him. This mutant later had a son who would come to be known as David Haller, a mutant with enough psionic prowess to manipulate reality around himself.
David would later be adopted by the Haller family, seemingly given away by his true parents in secret. The Shadow King, however weakened, survived his encounter with David's father, found David and inhabited his mind when he was a child. He would stay inside David for the remainder of his adult life, a second set of brainwaves hiding under David's own, planning to avenge himself and gain its former power and more through David. This would cause David to develop severe mental illness in the form of voices in his head, hallucinations, and intense emotional instability, which David would try to cover up through drugs.
The Shadow King was able to even able to manipulate David's memories, such as making David think he had a dog named "King" or remembering his friend and fellow drug addict, Benny, as a girl named Lenny Busker, who would eventually become a form taken by the parasite. Any encounter David would have with the Shadow King or whenever David would begin to notice the Shadow King as being behind his insanity, the parasite would erase this from David's memories.
The Shadow King's constant hold on David's life caused David to attempt suicide with an electrical cord he unknowingly manifested with his powers and get himself put in Clockworks Psychiatric Hospital, where he would essentially be held prisoner by the parasite. David was left unaware of this, as he was unable to discern reality from his hallucinations and would subsequently think the powers that he soon found himself with as part of his delusions.
- Possession: As a psychic and incorporeal being, the Shadow King is capable of inhabiting the minds of others, establishing a parasitic/symbiotic relationship with them as a result. This allows him to manipulate the host's memories, perception of reality and their overall mental and emotional state, even if the host is unaware of it. At his peak, he can take over a host's body completely and influence the physical world through them. Without a body, he can be perceived as black, shadowy smoke. Hosts of the Shadow King can sometimes have yellow or grey eyes or monstrously distorted voices. In fact, the parasitic mutant is capable of killing its host to assume full control, even if the host is mentally capable of fighting back.
- Telepathy: As a psychic being, the Shadow King is able to interact with other people's minds to either control their thoughts or manipulate their perception of reality. Due to being inside David Haller, he apparently was able to see through his eyes and share his senses, as he did while in the form of Lenny when talking to Sydney Barrett to watch him make his way to her before she left Clockworks.
- Illusion Casting: The Shadow King can induce hallucinations of himself or one of his forms, allowing him to appear to the people he chooses. His projections were powerful enough that when the team at Summerland were attempting to remove him using electromagnetic equipment to lock onto his set of brainwaves that where hidden by David's, he was able to project himself onto their video screens. It is also possible that his illusions of Lenny Busker were strong enough to be seen by people other than David, who he was possessing at the time, and that her corpse was manifested by David's powers when she was shown to be killed. Hallucinations or psychic projections of the Shadow King are often accompanied by the appearance of the color red, a blaring trumpet, or a shadowy black smoke.
- Astral Projection: The Shadow King is able to not only travel with others as a mental projection, but can even seamlessly travel to and manipulate the Astral Plane, an ability it used David Haller to regain when possessing him to gain its former strength. He could use it to imprison others that are inside the Astral Plane with him inside dream-like fantasies that can cause them to forget that they are in a fake reality. He was also able to percieve events in the real world from the Astral Plane, such as when he saw Oliver Bird attempting to shield David and Syd from bullets using letters conjured into thin air and allowing Cary Loudermilk to try to put a device on David's head to free him from the Shadow King's mental manipulation.
- Telekinesis: When projecting himself into the physical world and when possessing Kerry Loudermilk, the Shadow King demonstrated being able to manipulate the physical world with his thoughts, either to send people flying several feet or to control their movements like puppets. He was even able to crush and fold Walter from the inside out when they were in the Astral Plane, which caused his body to be crushed telekinetically in the real world. It is also possible that David's unstable telekinesis was actually caused by the Shadow King.
- Force Field Generation: While possessing Kerry Loudermilk, The Shadow King was able to generate a red aura of energy with shadowy smoke around himself, causing a pulse wave that expelled him from Kerry when colliding with David Haller's own energy aura.
- Longevity: Since he is not a physical being, The Shadow King does not age and has no definite life-span. Due to this, his true age is unknown.
- David Haller/Legion - Former Host and Victim
- Amahl Farouk - Former Host
- Professor X - Enemy
- Oliver Bird - Current Host
- Melanie Bird - Enemy
- Ptonomy Wallace - Enemy
- Sydney Barrett - Former Host and Enemy
- Cary Loudermilk - Enemy
- Kerry Loudermilk - Former Host and Enemy
- The Shadow King notably takes the forms of Lenny Busker, the beagle named "King", a living illustration of "The World's Angriest Boy In The World" (which he claimed was his favorite), and a silhouetted wild dog in a cage with red light.
- While the Shadow King was once invisible to others and David would be unable to remember seeing him due to its influence, Sydney Barret gained the ability to see and remember the Shadow King, seemingly after switching bodies with David. This caused the Shadow King to feel almost threatened by her presence and force him to act against her, especially when his control over David began to slip due to his attachment to Sydney.
- The Shadow King became fond of The Eye due to their common belief that power was what determined the worth of someone's existence.
- Shadow King's physical appearence of thin arm, long fingers, round stomach, round head and pale yellowish skin is strikingly similar to X-Men villain Mojo.