Why Marvel's Avengers: Earth's Mightiest Heroes Was Canceled

If you asked me what the finest adaptation of the Marvel Universe is, the 2010 cartoon "Avengers: Earth's Mightiest Heroes" would have to be up there.

It was the second attempt at an Avengers cartoon, after the best forgotten "Avengers: United They Stand." "Earth's Mightiest Heroes," from the moment it premiered on Disney XD, was much better. Developed by Marvel animation veterans Christopher Yost and Joshua Fine with director Ciro Nieli, "Earth's Mightiest Heroes" did what the (sadly short-lived) "Spectacular Spider-Man" did. It took the whole of "Avengers" comics, picked out the most famous stories and what worked, and streamlined a messy publication history into an epic saga.

Yost and Fine, as adult fans of Marvel Comics, were clearly writing with people like themselves in mind. But that wasn't to the detriment of young viewers! What kids got in "Earth's Mightiest Heroes" was a show that respected their intelligence and attention. The show introduced the central Avengers one by one across five episodes, before uniting them in the two-parter "Breakout." From there, the line-up rotates: some Avengers come, some leave, as roster flexibility has always been a big part of the Avengers.

The writers used those opening episodes to set up story arcs that came together after the Avengers did, balancing episodic and serialized storytelling. Baron Zemo (Robin Atkin Downes) and Enchantress (Kari Wahlgren) assemble the Masters of Evil to counter the Avengers, running through season 1, while season 2 builds its first half around "Secret Invasion." Big foes like Kang the Conqueror (Jonathan Adams) and Ultron (Tom Kane) get dedicated build-up and multiple episodes of focus.

The Avengers themselves are all depicted pitch-perfectly. The show does something that Stan Lee and Jack Kirby's original comics never managed — make the Hulk (Fred Tatasciore) into a core Avenger. The show has arguably the best depictions ever of Hank Pym (Wally Wingert), written as a pacifist who believes in rehabilitation, and his spunky partner Janet Van Dyne/The Wasp (Colleen O'Shaughnessey). This is the show that made my 13-year-old self angry that the 2012 "Avengers" movie left Ant-Man and Wasp out.

Speaking of — you'd think an "Avengers" movie would've been a boost for "Earth's Mightiest Heroes." Instead, the show got pulled that year, wrapping after two seasons and 52 episodes. As I've been asking for the last decade: what was Marvel thinking?

Less than a year after "Avengers: Earth's Mightiest Heroes" premiered, a new Avengers cartoon took its place on Disney XD: "Avengers Assemble." Developed by the studio Man of Action (Joe Casey, Joe Kelly, Duncan Rouleau and Steven T. Seagle), "Assemble" was what "Earth's Mightiest Heroes" wasn't. It was much more childish and simplistic, not to mention with lower-quality animation. Then again, it ran for five seasons and 127 episodes, so it did something right.

The premiere of "Avengers Assemble" tried to suggest it was a sequel to "Earth's Mightiest Heroes," but that pretense fell away quickly. That was likely just an opening move to ease kids away from one "Avengers" cartoon into another.

So, it can sound like Marvel traded down, putting forth a worse Avengers cartoon by killing a better one. But look at "Avengers Assemble" and you can see the true goal was synergy with the movies. "Avengers Assemble" used the team line-up from the 2012 movie: Iron Man (Adrian Pasdar), Captain America (Roger Craig Smith), Thor (Travis Willingham), Hulk (Mr. Tatasciore again), Black Widow (Laura Bailey), and Hawkeye (Troy Baker), plus Falcon (Bumper Robinson) as the team newbie.

The character designs were taken after the movies, as were the storylines. The first season of "Avengers Assemble" features the Red Skull (Liam O'Brien) hunting for the Tesseract, the MacGuffin of the 2012 "Avengers" film.

In the first announcement of "Avengers Assemble" back in June 2012, then-head of Marvel Television Jeph Loeb explained to TV Guide (and reported on by IGN) that: "The 'Avengers' movie has been the ambassador to the world for the Marvel Universe so we want a show that has the feel and the tone and the incredible adventures like that movie."

"Avengers Assemble" also appears to have been part of a streamlining effort by Marvel Animation. It was set in the same universe as "Ultimate Spider-Man," a Man of Action production which premiered on Disney XD in 2012. You can see some of that attitude seeping into "Earth's Mightiest Heroes" season 2.

The title sequence was replaced with Nick Fury (Alex Desert) narrating how the Avengers came together. This is even though the "Earth's Mightiest Heroes" Avengers were not affiliated with S.H.I.E.L.D. like the movie ones were. Yost also confirmed that his plans for the latter half of "Earth's Mightiest Heroes" season 2 were rewritten.

When Spider-Man guest-starred on "Earth's Mightiest Heroes," he was voiced by Drake Bell from "Ultimate," who dubbed over previously recorded lines Josh Keaton (who played Peter Parker on "Spectacular Spider-Man.") Tellingly, Betty Brant in "Earth's Mightiest Heroes" is voiced by Grey DeLisle, who voiced her in "Spectacular Spider-Man."

Now, "Avengers: Earth's Mightiest Heroes" at least got a finale — the Avengers bring together all their teammates and allies to defeat Galactus, who has arrived to consume Earth. It wasn't like Yost and Fine's "Wolverine and the X-Men," which ended on a cliffhanger after one season. But some threads still hadn't been tied up.

"Earth's Mightiest Heroes" season 2 was building up a big confrontation with the fire demon king Surtur (Rick D. Wasserman). It never came since Yost had intended him to be season 3's big bad. In 2020, for the show's 10th anniversary, Yost tweeted out a hypothetical 26-episode third season of "Earth's Mightiest Heroes" (read in full here). Keep in mind, this list isn't exactly what would have been made if Yost and co. got a season 3 pick-up, it's more of a wishlist. Still, it does reveal what Yost wanted to do in "Earth's Mightiest Heroes" season 3 and how he would've wrapped up lingering plot threads.

The first half of this hypothetical season 3 is very magic-focused, as Surtur takes center stage as the main villain. The season would introduce Doctor Strange, while Quicksilver and Scarlet Witch join the Avengers. Stories to be adapted include "Doomquest" (where Iron Man and Doctor Doom are sent back in time to Medieval Europe) and Thor becoming a frog, as in "Thor" #364.

The second half of the third season would bring in the X-Men (Professor X, Cyclops, Jean Grey, Wolverine, Nightcrawler, Storm, Shadowcat, Colossus, and Rogue), who aren't too happy about Magneto's children being on the Avengers. That would culminate in a season finale pitting Scarlet Witch against the Dark Phoenix.

The plans go further. In several now deleted tweets, Yost revealed "Earth's Mightiest Heroes" season 4, part 1 (or "Under Siege") would've seen Doctor Doom (Lex Lang) unite the most powerful villains of the world against the Avengers. Joshua Fine has also said the show had been planting the seeds for "Civil War" and season 4 "likely" would've paid them off. The second half of season 4, "Infinity Quest," would feature the Elders of the Universe searching for the Infinity Gems to end the universe.

Knowing these details is satisfying and frustrating since they sit unrealized. If it had been allowed to run its course, then "Avengers: Earth's Mightiest Heroes" would likely sit as Earth's mightiest Marvel cartoon.