2. The Kree-Skrull War (Avengers #89-97, 1971-1971)
When an intergalactic war between the merciless Krees and the shape-shifting Skrulls spills over onto Earth, it’s up to the Avengers to save our planet from the crossfire. Featuring the creative team of writer Roy Thomas and artists like Sal Buscema, John Buscema, and Neal Adams, this story is a precursor to the multi-part epics that Marvel would produce in the future. From the soil of Earth to the far-reaches of the Andromeda galaxy, The Kree-Skull War is an intergalactic epic of mammoth proportions.
Coupled with the copious amount of action in each issue, writer Roy Thomas' narrative also slipped in some social commentary, making it easier for a more sophisticated brand of reader could enjoy it. The Kree-Skrull War is considered by many to be the peak of Avengers storytelling, and there have been few story-lines since that have actually come close to topping it.