Corto Maltese Became DC Comics Canon In 1990
As I mentioned before, the setting of Batman: The Dark Knight Returns is in Earth-31 of the DC Multiverse, meaning that the nation of Corto Maltese had never originally existed in the main Earth-1 continuity of DC Comics. That was, however, until May 1990 when the country made an appearance in Issue #4 of the eight-part limited series, Time Masters.
Just four years later, Corto Maltese was given a shout out in Issue #31 of Batman: Legends of the Dark Knight, and in the somewhat meta Superman one-shot, Under a Yellow Sun, which was released the same year. Many years later, the nation had a recurring role in The Flash Vol. 5 in 2017 during the Rebirth era of DC Comics, and was most recently featured in the Damian Wayne-led Robin title in an issue released on July 27, 2021. That is about as far as Corto Maltese’s history in print goes, but it arguably has a more outstanding life in other forms of media.
Source: Cinema Blend
