Source: comicvine.gamespot.com

6. Secret Invasion

We already know that 2018's Captain Marvel will introduce the Skrulls to the MCU, and that gives us a nice window into the 2008 blockbuster storyline Secret Invasion.

That comic reveals that certain Marvel heroes and villains were abducted and replaced with Skrull sleeper agents. Then, when that programming broke down and they revealed themselves, the full-on Skrull battalion visited Earth. They were accompanied by a platoon of Super Skrulls, who’d each been gifted with the superpowers of three Marvel heroes.

Revealing that there are Skrull sleeper agents in the Avengers' midst would sure create a shake-up. In Winter Soldier, we had a taste of something similar with HYDRA (Sitwell, you bastard), but this would be on a whole "˜nother level. The Skrulls are scary villains with a unique ability to disappear and blend into the background. Their introduction would truly constitute an Avengers-level threat.

Plus, I like their bumpy, green chins.