While the release of WandaVision saw Marvel Studios' first TV series taking place in the MCU, this is far from the first series believed to be a part of the interconnected Marvel universe. 2013 saw the debut of Marvel's Agents of SHIELD a live-action series starring Agent Phil Coulson, following his team of agents traveling the globe on various super powered missions.
When The Avengers' director Joss Whedon announced his involvement in the early episodes, it was clear Marvel was series about taking its universe to TV with the ABC series. The first season featured appearances from superstars like Nick Fury, Lady Sif, and Stan Lee, with plot lines tying directly into Captain America: The Winter Soldier with Hydra's infiltration of SHIELD further explored on TV.
However, as time passed the series continued to move further away from the events of the movies and the connections began to be less and less prominent. Over time more series continued to be released which followed similar situations in which the show would frequently reference the movies, but not the other way around. As the scale of the Agents' missions continued to grow, it became increasingly hard to believe The Avengers and other heroes would be unaware of these world-ending situations.
As Marvel TV's time has now come to an end with the division merged into Marvel Studios under Kevin Feige, mounting evidence suggests that the studio could be looking to largely ignore these series in future MCU projects, as WandaVision has further teased...
WANDAVISION'S NEW EVIDENCE
As Agatha Harkness revealed her magical nature to Wanda and the viewers, she introduced the concept of the Darkhold, the book of the damned. From the series' brief explanation of the book, it seems to be filled with the knowledge of Chaos Magic — forbidden magic that Wanda's extreme power allows her to wield.
However, this isn't the first time to book has shown up in the MCU. It previously appeared in the fourth season of Agents of SHIELD in which it was used to create a virtual Framework world to trap the agents and create the villainous Aida a human body out of dark matter. Robbie Reyes' Ghost Rider sensed this and teamed up with the agents to defeat Aida, and take the book back to the dark dimension.
Agents of SHIELD isn't the only time to book popped up on Marvel TV as it was additionally featured in the third and final season of the Hulu series Runaways.
It was never explained exactly how Morgan Le Fay got her hands on the book in the Hulu series as she attempted to fulfill her plan to conquer Earth. All in all the book has a confusing continuity across the Marvel universe.
While the Darkhold shares the same design across Agents of SHIELD and Runaways, it has a distinctly different look on WandaVision — likely due to the series' higher budget allowing for a more intricate design. This leaves the question, are the Marvel TV series still canon to the MCU, or is this just another minor retcon?
THE EVIDENCE SO FAR
Agents of SHIELD's fifth season saw it dive into time-and-space travel, long before the movies did in Avengers: Endgame. The climactic finale of the time-travel season saw another world-ending threat face the planet as the movies addressed Thanos reigning down his invasion of Earth. And yet, no snap happened, half the population didn't disappear, leading to confusion for most.
The explanations of Endgame seemed to explain this result as it was revealed the consequences of time-travel result in the creation of new realities with different outcomes. From this, it could be simply assumed the Agents returned from their futuristic mission to a reality in which the Avengers successfully defeated Thanos and prevented the attack.
And the final season of the series confirmed this theory by revealing they were living in a new reality and there was a way back to the old one. However, the point of time they returned to should have been during the five-year time jump of Endgame, but it's clear this wasn't that world as nothing seemed to be affected by the tragic loss of billions.
SO IS MARVEL TV CANON?
It's unlikely fans of the classic Marvel TV series will ever get a clear answer to their status within the MCU. Characters likely to reappear include the likes Daredevil and potentially Agents of SHIELD's Daisy Johnston/Quake, however, it's unlikely they would ever reference the series' past events and would instead be introduced as new characters with the same actors.
The return of the Darkhold with a new appearance shouldn't be taken as too much evidence for or against the canonization of past TV series. After all, characters like Rhodey and Bruce Banner have already been recast in the MCU, and yet Iron Man and The Incredible Hulk are still considered canon.
If Marvel ever plans to provide answers to the fate of their cable TV heroes, Doctor Strange in the Multiverse of Madness is the perfect place for them to do it as the series can simply be revealed to take place in an alternate dimension.
Marvel ran numerous series across Netflix, Hulu, and ABC TV throughout the eight-year run of Marvel TV producing live-action MCU content. Meaning many classic comic characters were used up throughout, this makes it likely Kevin Feige may want to reuse some down the line, likely forcing a recast.
In comparison to the fan base of the blockbuster movies of the MCU, the number of people who have viewed any of these TV projects is minuscule. Overall, it's unlikely the studio will ever provide a definitive answer to whether or not anything from Marvel TV is canon, but will instead continue to ignore its existence to focus on their own stories.