Viper King

His specific age is unknown, but we do know that despite having recently hatched, he was already breeding with female Vipers, suggesting that he matured and reached reproductive capacity extremely quickly.

Not much is known about his personality, but there is a recording from Dr. Vahlen stating that Viper King (designated "Subject Gamma") displayed alarmingly intelligent behavior, suggesting that, unlike common Vipers, he possesses superior cognitive ability, although this intelligence is primarily manifested through his dangerous effectiveness in combat. He cannot talk, but he could be taught how to communicate through signs.

The Viper King has an elongated, reptilian appearance, similar to the standard Vipers but larger and more robust. It is the only known male Viper. Its body is long and serpentine, and it is equipped with a prehensile tongue that it uses to attract its enemies. Unlike regular Vipers that spit venom, he spits out a cloud of gas that freezes his targets. He carries a Bolt Caster as a weapon and has armor that makes him more resistant. His overall design makes him resemble a more powerful and regal version of his species.

The Viper King was engineered by former XCOM Chief of Research Vahlen, a German scientist who became separated from XCOM after the destruction of XCOM's headquarters in 2015. While still an an embryotic state Vahlen altered the egg that would hatch into the Viper King. Among the changes to genetics was the change of sex from female to male. Vahlen had envisioned the Viper King as an entity that would control matured iterations of newly hatched Vipers (the aliens) she found in an abandoned alien facility. Her plan was to use the King to control an army of them for use in combating ADVENT's rule. However after one of the Viper's tried to speak to her in English she freaked out and killed it and then began an autopsy to figure out how it could speak (she had become rather less sane by that point). The Viper King then rebelled against Vahlen and killed her, eventually leading his group into the outskirts.