“Oh ho oh... Poor Angstrom, ho ho.. You actually thought you could hide from me? My god... Look at you. Pathetic! You're really making me feel bad, man. I'll tell you what-... I'll kill the boy quickly." ~ Sinister Mark threatening a variant of Angstrom Levy and his kid.

Little is known about Sinister Mark's past, but it's implied that most of his life had been similar to the mainstream Mark's, with the exception that something had made him closer to his father, leading him to a darker path that culminated in him joining the ranks of the Viltrum Empire.

According to him, his world's version of Firebreather is the king of all monsters and one of the most ferocious villains he had ever faced during his time as a superhero, which could lead to the hypothesis that everyone is a little more "evil" in Sinister Mark's dimension. It's also mentioned by the Masked Mark that, sometime after becoming a villain, Sinister Mark had murdered his own mother, Debbie, in their own home, which made him hate coming back to that place.

In the animated series, it's shown that during his reign of terror, he had terrorized his version of Angstrom Levy and his son, Angstrom Levy Jr., before killing the latter in front of his very own eyes. He also admitted to have murdered his dimension's version of his father.

Invincible War Sinister Mark was approached by the mainstream Angstrom Levy to aid him in ruining his home dimension's Invincible’s reputation and, in exchange, Levy would help his empire expand across universes. He accepted the offer and was among the wave of Marks that stormed the mainstream Image Comics universe. On the first day of the invasion, he would go to Nevada, where he faced off against this universe's version of Firebreather. He pointed out how weak and pathetic he was in comparison with his universe's Firebreather, before finishing him off rather quickly.

Later on, by the end of the second day, Sinister Mark is seen fighting Oliver Grayson, who he intuits is an interbreed Viltrumite, or as he puts it a "kind of lesser Viltrumite". It's unknown how Oliver survives the encounter.

On the third day, Sinister Mark had fully decimated an entire city, before being called to regroup by Angstrom on top of the Grayson Family's home. Sinister Mark points out how he hates going back in there, only for the Masked Mark to reply that not every one of them had killed their mother in there and that he actually liked to see it again. Angstrom Levy then makes act of presence, and asks the Evil Invincibles a last favor: to bring this dimension's Invincible to him so he could disfigure him himself.

Sinister looks physically identical to his main timeline counterpart, having black hair with a widows-peak that is combed back with a few strands sticking up along with a lean and defined build. The only noticeable difference between the two is that Sinister appears paler compared to the main Invincible.

Sinister Attire Sinister Invincible wears a similar outfit but unlike the main version of Invincible, his is black and yellow. The outfit also possesses a large yellow cape, fingered yellow gloves (as opposed to the original's fingerless ones), black visors on his mask, and a lack of knee pads. Other noticeable differences in Sinister's costume is that the bottom of the "i" on his chest does not have a point and his mask's face cutout doesn't overlap with the visors, unlike the main Mark's costume.

Personality Sinister represents a terrifying escalation of evil, surpassing even the most depraved of his predecessors. He's a psychopathic killer, utterly devoid of humanity, whose brutality and sadism mirror the most heinous serial offenders. Driven by a relentless, single-minded focus on his objectives, particularly killing, he wastes no time or energy on anything but their swift and brutal completion. His usual outward personality depicts a cool and malicious His volatile aggression manifests in constant outbursts of anger and verbal assaults, making him a perpetually dangerous and unpredictable force.

Abilities and attributes:

Hybrid Viltrumite Physiology: Sinister possesses all the powers of his main timeline counterpart. He is a Human-Viltrumite hybrid, though his Viltrumite genes overshadow his Human genes, making him almost a pure-blooded Viltrumite. Unlike the main Invincible, however, Sinister appears much more adept at using his powers and does so in an even more vicious manner. Decelerated Aging: Sinister possesses an extraordinarily lifespan. This stems from his body gradually aging slower the longer he lives. From this, it allows him to retain his health, vitality, conditioning, performance, and youthful appearance that much longer, potentially able to live for thousands of years and still be in his prime.

Flight: Sinister can levitate himself in the air and propel himself in any direction he desires, able to alter his trajectory mid-flight, letting him maneuver seamlessly through various environments. He is also able to fly through space. Nigh-Invulnerability: Sinister body is incredibly resilient, allowing him to withstand a wide range of attacks without sustaining any significant harm. He is unfazed by virtually any environment, or lack thereof. He can walk away unscathed from explosions, bullets, and even powerful energy-based assaults. Reactive Adaptation: Sinister exhibits remarkable resilience and adaptability, displaying a propensity for continual growth and improvement throughout his lifespan. His physical strength, speed, and durability progressively augment in correlation with the level of adversity he faces or the severity of injuries he recovers from. Moreover, his combat experience fosters an innate ability to assimilate knowledge and insights from past encounters, enabling him to refine his tactics and enhance his efficiency in subsequent engagements. Regenerative Healing Factor: Any injuries that Sinister does sustain and survive, he can recover from in a day if not mere minutes. He can restore broken bones, torn muscles, damaged organs, even regrow lost anatomy with no lingering signs. Likewise, he is virtually immune to almost all forms of illness and contamination. Superhuman Lung Capacity: Sinister possesses the remarkable physiological ability to sustain his breath for extended periods of time, spanning several weeks. This allows him to endure the harshness of space unprotected and make interstellar travel. Superhuman Senses: Sinister possesses an exceptional auditory perception far surpassing human capabilities, allowing him to discern sounds emanating from considerable distances and selectively drown out specific noises. His vision is equally advanced, able to discern distant objects with the same clarity as though they were in close proximity. Likewise, this grants him an equally powerful equilibrium and balance, able to maintain his stability and poise even in challenging situations. Superhuman Speed: Sinister can move at tremendous speeds, able to travel anywhere in the world in mere minutes. Likewise, he can close short distances too fast for normal humans to even register, able to reach in short bursts, he can close slip past Angstrom and capture his son before the father could realizes it happened. Superhuman Stamina: Sinister can sustain physical exertion for prolonged periods of time without showing any signs of exhaustion. He can likewise endure some of the most grievous of injuries that would instantly kill a human, excluding too much harm to his heart or brain. He can go for several weeks without sleep or sustenance unhindered. Superhuman Strength: Sinister exhibits the ability to lift and press several tons, showcasing immense physical strength that allows him to confront powerful adversaries.