I do not fear death. I have died before. ... Mar-Vell is a Kree name. Mar-Vell was the name I was given. I have protected the earth from mania and treachery. I have fought alongside the mightiest Avengers. I have seen the glory of humanity in all forms. I have shared bonds no Kree has ever felt. I have seen the entire universe. I know all there is of life and death. Mar-Vell was the name I was given. Mar-Vell was the name I was given.
As part of their overall invasion strategy, the Skrulls genetically engineered one of their race to be an exact replica of the Kree hero Mar-Vell. Infecting him with the same strain of cancer the real Mar-Vell fell victim to and implanting false memories to make him believe he was the real hero. In order to eventually recall him to their side when the invasion was underway, a random Earth painting was to be inserted into his mind as a trigger. However, Khn'nr awoke during the procedure and the Skrulls erased the memories of the real Khn'nr. Believing himself to be the real Mar-Vell, he went wild, slaying the Skrulls and escaping into the Negative Zone.
Lost in the Negative Zone, Khn'nr, who only had access to the memories of the true Mar-Vell, forgot how he had come to be there. During this time the recently reawakened hero Sentry began exploring the Negative Zone through an access point in his Watchtower. During one of these expeditions, he discovered and retrieved "Mar-Vell", bringing him back to Earth. When scans erroneously revealed him to be the real hero, it was believed he was a time-displaced Mar-Vell and the heroes happily welcomed him back. Afraid of alarming the public with the return of a dead hero, "Mar-Vell" was placed in charge of the Negative Zone prison, 42, while the heroes engaged in a Civil War on Earth. Eventually, during the final battle of the War, "Mar-Vell" was activated alongside the Order and fought briefly against the anti-registration heroes, briefly being seen by Spider-Man in the conflict, though most either failed to see him in the chaos or dismissed him as another clone, similar to the Thor clone.
After being revealed to be alive, "Mar-Vell" sought to escape the hectic super-hero life and journeyed to Paris to visit the Louvre, where he came upon the very painting that had been set as the trigger to awaken his full memories, but because the process had been flawed, it merely triggered a sense that he was meant to remember something. At this point a Skrull impersonating the deceased villain Cyclone attacked the art museum, but was quickly defeated by "Mar-Vell".
Returing to New York City, "Mar-Vell" assisted the Mighty Avengers in destroying a rampaging robot, inadvertently revealing his presence to the world. Seemingly in response to this revelation, a religious cult calling themselves the Church of Hala sprang up, a cult that based its beliefs around the returned Mar-Vell, but was in actuality another part of the same Skrull plot that spawned "Mar-Vell".
Newly "returned to life", "Mar-Vell" was sought by his "old friend" Ms. Marvel and during a conversation, the two were attacked by another thought-dead villain, Cobalt Man, who was quickly defeated and taken into SHIELD custody. In custody he was interrogated by "Mar-Vell" and revealed to be a Skrull, also claiming "Mar-Vell" to be one. Believing the claim to be false, "Mar-Vell" quickly left and while discussing the matter with Tony Stark, the two were attacked by a Kree army group. Defeating these foes, they were also revealed to be Skrulls.
Growing enraged at the world, "Mar-Vell" fully returned to the world, intending to use his power to help the world, not just fight super-villains. Doing this meant going against Stark's wishes, and with the lingering doubt of his true identity (alongside the revelation of Elektra being a Skrull), Stark used Ms. Marvel to seek him out, using an alternate pair of Nega-Bands to shunt the hero to the Negative Zone. Once there, "Mar-Vell" found his way back to the original Skrull lab where he was created, and remembered his true origin. With the heroes believing him returned to his true time, "Mar-Vell" returned to the world, claiming he was going to help protect it, regardless of his origins.
During the start of the Skrull Invasion, he attacked the Thunderbolts, seemingly going against his claim of wanting to honor the true Mar-Vell. He defeated the villain team, but their leader, Norman Osborn, talked him into helping Earth. He then flew into space and tore through several Skrull ships that were chasing Mr. Fantastic and Agent Brand. He destroyed many of the fleet but was attacked by a Super-Skrull which killed him.
Barely alive after his effort, he managed to crash back on Earth, crossing Noh-Varr's path, who briefly mistook him for the original Mar-Vell. Before passing of his wounds, Khn'nr spurred Noh-Varr into continuing Mar-Vell's legacy as the protector of Earth, branding with his dying words the Skrulls as liars and traitors and that he defeat the Skrulls and take on the mantle of Captain Marvel, which he did as he joined the Dark Avengers under the name Captain Marvel.
Skrull Shape-Shifting: Like other Skrulls, is a shape-shifter. They can mentally cause the unstable molecules that comprise his or her body to become pliant, enabling him or her to assume other forms through muscular expansion and contraction. Once a new shape has been assumed, it takes a conscious act of will to assume another form or revert to natural. Hence, Skrulls do not spontaneously lose their assumed form when asleep or unconscious. Skrulls in altered form will, however, revert to their original forms at the moment of death. However this ability was dormant.
Skrull infiltration Ritual: The Skrull took part in a ritual a mixture of science and magic that imbued them with the powers and memories of the selected subject. This allows the subject to go undetected in human form by Iron Man's technological scans, Charles Xavier's mental scans, Spider-Man's Spider-Sense, Wolverine's animal senses, or any other conceivable forms of detection. So subtle and powerful is this form of concealment neither Doctor Strange can detect the Skrull with the Spell of Tartashi, nor could the Elder God-powered Scarlet Witch using Xavier's psychic powers delve past the memory blocks.
Skrull Military Training: is a trained Skrull soldier.
Aviation: is trained in the use of the advanced warp-drive starships of the Skrull-military.
Unarmed Combat: is trained in the unarmed combat of the Skrull-military, he is also quite experienced; due to his involvement in the Kree-Skrull War.
Marksmanship: is trained in the use of the ranged energy-weaponry of the Skrull-military.
Skrull Shape-Shifting: Skrulls only take on the appearance of an object or person and none of that object or person’s characteristics. There is a limit to the size of the object or person a Skrull can imitate. The average Skrull cannot distend his or her mass any more than 1.5 times as large a volume as his or her original volume, nor can he or she contract his or her mass any more than 0.75 a volume as his or her original.