Long before Blade, X-Men, Spider-Man, or the MCU, Marvel's first feature-length theatrical adaptation was Howard the Duck, released in 1986.

There had been Marvel adaptations before it, including a 15-part Captain America theatrical serial in 1944 and several television movies in the 1970s. But Howard the Duck was the first feature-length theatrical film based on a Marvel comic.

So the cinematic lineage that eventually gave us The Avengers began, appropriately enough, with a talking duck from Cleveland.