MCU fans know how Thanos, in his attempt to secure the Soul Stone, killed his favorite adopted daughter Gamora, in Avengers: Infinity War. He also mutilated and cybernetically enhanced his other daughter Nebula when her combat skills fell below his high standards. However, his treatment of his daughters in the movies pales next to what he did to his other children in the comic book version of the Marvel Universe.
Comic book fans know that Thanos had a few other children in the Marvel Universe, including his son Thane. What is not so commonly known is that Thanos sired many more children in his youth, possibly numbering in the hundreds. So, why haven’t any of these children popped up in current stories? The answer is very disturbing.
In Jason Aaron and Simone Bianchi’s miniseries Thanos Rising, readers learn that, after killing several people on his homeworld Titan, a young Thanos felt genuine remorse for his actions and vowed to never kill again. To make good on his promise, he left Titan and became a navigator on a pirate ship. This job enabled him to travel to multiple worlds — far more than he knew existed — and meet many alien women. Hoping to gain some semblance of a normal life, Thanos slept with women across the galaxy and sired children with nearly all of them.
Although all of the births were healthy, Thanos felt that none of the children looked like him and all of them resembled their mothers (although this may have been due to his personal perception). Recalling how his own mother had tried to kill him when he was born because she thought he was a monster (something he later admitted she should have done), Thanos often looked at his own children, wondering if there was a monster in them — or if that monster was only in him. Despite these misgivings, Thanos never mistreated his children but often left soon after they were born.
Thanos left his children in the charge of their mothers, who recognized that Thanos was often distant but held out some hope that he was a good man (or at least not a cruel one). While this may have been true at one point, eventually Thanos came to realize that he only loved one woman — a childhood friend who later claimed to be Death. When Thanos swore he would make her love him, the woman told him he would have to show her that he would belong only to her and to no others.
To show his resolve, Thanos returned to a planet where one of his many lovers was waiting with his son. Overjoyed, the woman rushed to Thanos and presented him with their son — only for Thanos to kill first the boy and then his alien lover. When Thanos asked Death if this was enough, Death simply asked him if these two were all of his lovers and children. Realizing what Death was asking of him, Thanos proceeded to return to every planet where he sired an offspring and kill all of his children and his lovers. Eventually, death became so commonplace for him that it lost virtually all meaning, making it much easier for him to become the mass murderer most people know.
Of course, Thanos would eventually have other children at different points in his life (whom he wouldn’t kill right away), but his treatment of his early offspring was certainly horrific. Thanos claims to kill impassively and even “mercifully,” but his early kills were anything but compassionate.