The Chitauri (and Leviathan) debut in the Marvel Universe.

Avengers Assembled villains, Loki’s Henchman and Thanos’s pawns The Chitauri will be debuting in Nova #4. It isn’t yet known if they will be in any way close to The Chitauri featured in Marvels The Ultimate (as part of the Ultimate universe) where they were a shape shifting invasion force in the mold of the Skrulls. Coincidentally the Skrulls later became part of the Ultimate Universe though they couldn’t shapeshift. However physically they will be extremely similar to the Avengers Chituari.

This can only be considered a good thing, One of the weak parts of the movie was the invading force weren’t particularly expanded upon in any way so seeing them enter the mainstream Mythos of Marvel (616) will help to flesh them out much further.