Board Thread:Questions and Answers/@comment-5933274-20150905203757/@comment-61022-20151022130637

The Ultimate Chitauri were basically the Skrulls of the Ultimate universe. Marvel brought them into mainstream Earth-616. Likely to differentiate them FROM the Skrulls. It's probably some rights issue for film licensing. I would not be surprised if the Skrulls are tied up in the Fantastic Four movie rights and putting the Chitauri from and center is Marvel's way of sort-of-kind-of-not-really getting around that.. Because you know, there are like no other viable alien races they could use from their already well established continuity :P