There is no denying that the Marvel Cinematic Universe is massive: there is no easy way possible to keep up with all the characters who have come and gone from Marvel movies and television shows. Some characters, though, leave a mark and become favorites. Others sort of fade out into obscurity, forgotten by both Marvel and fans alike.

There are those iconic Marvel characters that always leave an impression, even if their time in the MCU is short. Those characters stay with fans for a long time after their last appearance, even if that appearance was the result of their death. Sometimes, fans desperately want to see those characters return to future movies and TV shows. Sometimes, though, fans are shouting "good riddance" to characters that they never want to see again.

Many of these characters are still sort of just out there in the MCU, seemingly abandoned by those people who created them. At this point, there are many such characters, although no Marvel fan might agree on which category those characters fall into: those who should return and those who should go.

Here are: 8 Abandoned MCU Characters That Need To Come Back (And 7 That Should Stay Gone).

Come back: Peggy Carter

One of the most beloved characters in the Marvel Cinematic Universe is Peggy Carter, who made her first appearance in Captain America: The First Avenger. Sure, she was a character from World War II, but she was so popular that she had two seasons of her own TV show: a series that ABC canceled way too soon.

Peggy has appeared in movies in flashbacks, with her character passing away in Captain America: Civil War. But that doesn't mean that she couldn't come back in more flashback scenes, both in the movies and on Agents of S.H.I.E.L.D., especially considering that she was one of the first members of that agency.

The Agent Carter television show never got around to showing that part of her life and fans would love to see her return.

Stay gone: Inhumans

Marvel Shows Inhumans

Even before the first episode aired, it was becoming pretty obvious that Marvel made a huge misstep with its Inhumans television series. It almost seemed like the writers and costume designers just phoned it all in, and by the time the show made it to TV, it was already considered a huge flop.

That's why Marvel abandoned the series after one season and will probably never return to the concept, at least not in the way the company originally presented it. It was a huge departure from the comics and the only character fans might ever want to return is Lockjaw, the massive dog that has the power of teleportation. The other characters, though, can stay gone for good. No one wants to see a Medusa who lost her hair and her powers, or that poor excuse for Black Bolt.

Come back: Jane Foster

One character that Marvel fans really miss is Jane Foster, who appeared in the first two Thor movies as Thor's love interest. Actress Natalie Portman not only did the character serious justice, but she also left fans wanting to see more of Jane. However, the most recent Thor movie, Thor: Ragnarok, made it clear that Thor and she were no longer an item and that Jane was out of the picture, which left Marvel an excuse for leaving the character out of its cinematic universe.

In the comics, Jane eventually became Thor, and fans would love to see Portman tackle that part of the role.

Jane did not get the credit she deserved in the Thor movies, and she needs to come back so that her character gets her due.

Stay gone: AIDA

One of the most annoying characters to appear in the Marvel Cinematic Universe was AIDA, from Agents of S.H.I.E.L.D. She was the android that nearly took over the world (and took over the Framework as Madame Hydra), but she was just really not that interesting of a villain.

Only so much smirking and evil eyebrow-raising could make her android face remotely fascinating.

The television series beat the whole AIDA plot into the ground and for many fans, it got old really fast. She also made S.H.I.E.L.D. look really stupid because they seemed to think early on that a self-aware robot would totally be okay with getting exposed to the Darkhold, which is what, ultimately, turned her evil. Do they not watch science fiction movies at all?

Come back: Lady Sif

Marvel has really given Lady Sif the short end of the stick. They created this amazing female Asgardian warrior character and then immediately put her on the sidelines, save for a short appearance in Agents of S.H.I.E.L.D. Fans first met her in the first Thor movie, and got a good look at what she was capable of. She became one of the most appreciated warriors of Asgard, but Marvel abandoned her.

In Thor: Ragnarok, Loki (disguised as Odin) mentioned that he had banished her from Asgard.

So she's banished, so what? Fans would love to see her return, perhaps fighting by Thor's side in Avengers: Infinity War. If anyone could take on Thanos, it's Lady Sif. Who wouldn't love to see that?

Come back: Bobbi Morse

Adrianne Palicki as Bobbi Morse Mockingbird in Agents of SHIELD

Although Bobbi Morse never quite became the Mockingbird that her character had been in the comic books, she was still a solid member of Agents of S.H.I.E.L.D. A lot of this had to do with her portrayal by Adrianne Palicki, who gave fans a tough female character that still had a soft spot for her ex.

Her character, along with that of her ex, Lance Hunter, even got their own TV pilot, but ABC pulled the plug on the series before a single episode ever aired. The characters were written off on S.H.I.E.L.D., though, becoming fugitives that had to go into hiding.

Although Lance did briefly return to the series, Bobbi is long gone, with Palicki now co-starring in The Orville. But that doesn't mean that Bobbi should disappear for good.

Stay gone: Trevor Slattery

Trevor Slattery in All Hail the King

Iron Man 3 feels like it was such a long time ago, but many Marvel fans remember the villain from that movie, The Mandarin, partly because of the weird twist that the character's story took about midway into the film.

The Mandarin was the archenemy of Iron Man, and a terrorist, but then he wasn't, because it turned out that all the videos and photos of him that got sent Tony Stark's way were actually of an actor named Trevor Slattery who was just the public persona of the villain.

It was all such a convoluted mess that even Ben Kingsley couldn't save the character from becoming hated by fans.

For an actor, Slattery was completely clueless about the consequences of his actions and it's probably good if he stays gone forever.

Come back: Red Skull

One of the most terrifying villains in the Marvel cinematic universe is probably Red Skull, a German ex-SS officer who was also a brilliant scientist. Eventually, he became Red Skull and used his Nazi ideals in founding HYDRA. He was cut throat and never took no for an answer. He was not the kind of villain that fans identified with, but the one that had them sleeping with one eye open at night and that's what made him so great.

At the end of Captain America: The First Avenger, he gains control of the Tesseract and touches it: it supposedly obliterates him and sends what's left of him to Yggdrasil. With his ending left so up in the air, bringing him back would not be much of a stretch.

Stay gone: Darcy Lewis

Kat Dennings as Darcy Lewis

There was nothing particularly wrong with Thor character Darcy Lewis per se, but she got a little annoying, especially when she kept voicing her observations even when the other scientists did not want to hear them Granted, she was right sometimes, so fans have to give her that. She's one of those characters that no one really remembers and her presence sort of took away from the character of Jane Foster, who should have probably spent more time in the spotlight in the Thor movies.

In Thor: Dark World, Darcy sort of takes Jane's place as the "scientist character" and it felt way too obvious that this was her purpose in the movies. There is no mention of her in Thor: Ragnarok, and that's probably a good thing.

Come back: Blizzard (Donnie Gill)

Donnie Gill

When it comes to abandoning cool characters, Agents of S.H.I.E.L.D. seems to have it down pat. One character that fans keep wanting more of is Donnie Gill, aka Blizzard.

Donnie had really cool ice powers, but the shy S.H.I.E.L.D. Academy student never quite got enough screen time on the series.

However, when he was on the run from HYDRA, he did a pretty good job of fighting off agents from that organization. In the end, he got left behind, supposedly struck by sniper fire. He went over the side of a ship, but as he sank in the water, a cocoon of ice wrapped itself around him, suggesting that he did not lose his life. Fans think that it's about time that his story get resolved and bringing him back is the best way to do that.

Stay gone: Kilgrave

Kilgrave is the scariest kind of villain. He seems charming and gentlemanly on the surface, but his words have a way of manipulating people into doing anything he wants them to do. He used this power most often on Jessica Jones, even forcing her to take someone's life. He is probably the creepiest villain in the entire MCU.

Although Jessica took him out in the first season of the Jessica Jones series, Marvel brought him back as the little voice inside Jessica's head in season two. Eventually, that voice faded away, and that's where Kilgrave should stay forever: as a bad memory inside Jessica's head. The amount of Kilgrave we already got is just perfect - there's no need for more.

Come back: Janet Van Dyne

Disney loves its storylines that involve heroes with no parents. Nearly every movie made by Disney has a hero in it that survived losing at least one parent. Then Disney bought Marvel and Ant-Man comes out, and yes, there's a parent missing in the Van Dyne family.

Janet Van Dyne wasn't just a mother: she was the original Wasp.

The current Wasp, Hope van Dyne, Janet's daughter, believed that her mother lost her life in a plane crash for years, because that's what her father told her. Her father eventually came clean and admitted that Janet got trapped in the quantum realm during a mission as Wasp. It's likely that she's still alive and can possibly get saved. Here's hoping that this is the plot of the upcoming Ant-Man and the Wasp movie.

Stay gone: The Collector

The Collector in the MCU

Disney and Marvel love to introduce those weird little one-off characters and then let them just sort of reside in fans' minds without ever bringing them back. Sometimes, that can be a very good thing. Take the over the top character of The Collector, Taneleer Tivan, as portrayed by Benicio del Toro, for example.

In Guardians of the Galaxy, he meets with Gamora and analyzes the Orb for her. Of course, that meeting went sideways when Ronan and his team attacked the fortress, which resulted in most of Tivan's collection getting destroyed. Fans later learned that Tivan escaped through a scene that had him sharing a drink with Howard the Duck. Sure, Tivan was fun for the moment, but he should probably just stay gone at this point.

Come back: Justin Hammer

Justin Hammer MCU

Justin Hammer is one of those characters that fans still talk about long after a movie. In Iron Man 2, he was one of Tony Stark's main business rivals and did his best to stay under Tony's skin. But he wasn't the genius he made himself out as: he used money more than his brains. Greed got in the way after he tried to have the Iron Man suit stolen, which landed him Seagate Prison.

Portrayed by Sam Rockwell, Hammer was a charismatic character, and one that fans might like to see escape.

Imagine him heading up his own villainous group, going after Tony every chance he could get. The idea of Tony having that constant thorn in his side is a fascinating one, and would help keep his large ego in check.

Stay Gone: Grant Ward

Grant Ward was one of those characters that Agents of S.H.I.E.L.D. just couldn't seem to get rid of. Originally, he was a S.H.I.E.L.D. agent, but the series revealed that he was actually HYDRA posing as S.H.I.E.L.D. The team caught that way too late, but they eventually defeated him and left him on an alien planet. But that wasn't the end of Ward.

He then came back as Hive. S.H.I.E.L.D. defeated him again and he passed. but that didn't stop the show from bringing him back in the Framework as a digital version of himself. This time, he was actually one of the good guys. By that point, though, fans were kind of tired of the character, so it lost a lot of its dramatic effect. Hopefully, this time, he's gone for good.

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Which MCU character do you miss the most? Let us know in the comments!