Wikipedia
Chitauri
The Chitauri are a fictional race of extraterrestrial shapeshifters that appear in publications by Marvel Comics's alternative universe, Ultimate Marvel, in the limited series The Ultimates. They were created by Mark Millar and Bryan Hitch. They were created for the Ultimate universe franchise in place of the existing Marvel Comics alien species, the Skrulls, which play a similar role in the franchise's mainstream continuity. Later, Marvel would choose to distinguish between the Skrulls and Chitauri of the Ultimate universe. The species would later be adapted to other media, notably appearing in the 2012 film The Avengers as an invasion force led by Loki and even in the main Marvel universe.