A posthuman is a being whose basic capacities so radically exceed those of present humans as to be no longer unambiguously human by our current standards.

The first half-dozen posthumans who made their presence widely known appeared during World War 2, as part of the Red Army fighting the invading forces of Nazi Germany. Soon, similar groups of posthumans appeared, fighting for the Axis (primarily in Europe and Africa) and for the Allies (primarily in Europe and the Pacific).

Despite their incredible powers, posthumans have had a subdued effect on world affairs. Posthuman geniuses have given mankind extraordinary scientific and medical advances, but in nearly all cases these advances have been released gradually by the governments of the world (ostensibly to prevent the destabilizing influence of sudden leaps in technology).

Similarly, at the behest of conventional authorities, posthumans have generally refrained from involvement in everyday politics and diplomacy. The exceptions to this rule have traditionally been condemned as terrorists and threats to all of humanity. This phenomenon was most evident during the McCarthy era, when a small group of politically active posthumans calling themselves the Committee For The Advancement Of Mankind were convicted in absentia of violating the Smith Act.

There are fewer than 800 posthumans worldwide. Approximately 200 of these are in North America, roughly 100 of which are in the United States. Posthumans, particularly those who originate in the Americas, have a slightly greater than average tendency to migrate to the United States.

Most posthumans have the same thoughts, feelings, and behaviour as ordinary humans. These behaviours are the result not only of their individual experiences and environment but also of what happened to their ancestors millions of years ago. As such, human nature is shared, to a large extent, by everyone on Earth, even posthumans. Like most human beings in the Kalos Universe, posthumans are selfish and seek to improve their own conditions at the expense of others. At the same time, human beings have a great capacity to cooperate and display enormous depths of compassion, even toward people they have never met, and so do many posthumans.