The Marvel Cinematic Universe has evolved in a number of major ways in its decade-long existence. This has involved introducing new characters with every new film and expanding to explore new elements of the overarching Marvel story. However, that also involves leaving certain characters behind.
On that note, and now that Avengers: Infinity War is doing insane work at the box office, we have put together a list of long-gone MCU characters that we don't expect to see return to this franchise anytime soon. We have several to get to, so let's start things out with Jane Foster's spunky sidekick.
Though Marvel seems to have finally found its stride in its efforts to make Thor a comedic character, the pre-Thor: Ragnarok MCU films largely relied on funny supporting characters to play off of the God of Thunder. In that regard, Kat Dennings' Darcy Lewis stands out as one of the most notable of the bunch, but we haven't seen her since 2013's Thor: The Dark World. The political science major was one of the first people (along with Jane Foster and Erik Selvig) to meet Thor Odinson, but something tells us that we shouldn't get our hopes up about seeing her again anytime soon.
'Thunderbolt' Ross (William Hurt) may have returned to the Marvel Cinematic Universe with the releases of Captain America: Civil War and Avengers: Infinity War, but his daughter has remained notably absent from the MCU since 2008's The Incredible Hulk. Betty Ross (Liv Tyler) is the beloved love interest of Bruce Banner in the comics and in the first MCU Hulk movie, but it looks like the franchise has mostly moved on from her. After all, with Hulk and Black Widow (Scarlett Johansson) now an item (sort of), there's not much room for Betty in the equation. It seems that she's retired with Ty Burrell's Leonard.
One half of the villainous equation in Iron Man 2, Sam Rockwell's Justin Hammer was framed as a dark mirror to Tony Stark -- albeit far less charming or charismatic. The creator of the War Machine armor, Hammer was taken into custody by S.H.I.E.L.D. agents at the end of the film, and we haven't seen him since. That said, the Hammer name has been dropped several times across the MCU, such as in Season 1 of Luke Cage. Justin Hammer probably won't return to the MCU anytime soon (Rockwell seems to have moved on), but his influence continues to sway certain storylines and weapons that we see in this franchise.
The Marvel Cinematic Universe has a long history of straight up killing bad guys in movies, which makes the presence of Abomination so interesting. Unlike many Phase 1 baddies, Emil Blonsky (Tim Roth) actually survives the events of the film and is taken into custody. However, we never actually see him after Hulk beats him in Harlem. Agents of S.H.I.E.L.D has already implied that Blonsky is imprisoned in a secret government facility, and it very much looks like that's where he will remain for the foreseeable future. It's almost a shame; one would think that he could've been a serious help in Avengers: Infinity War's Battle of Wakanda.
Back in Phase 1, it seemed like The Incredible Hulk was going to set up a large corner of the Marvel Cinematic Universe. One such element teased for a future sequel was the creation of The Leader when Dr. Samuel Sterns (Tim Blake Nelson) found himself exposed to a vial of Bruce Banner's gamma-infused Hulk blood. The character's skull began to expand and pulse after the accident, with the obvious implication that he would go on to become a major player in Bruce's life as a hero. Alas, the MCU moved on from telling Hulk stories after bringing Mark Ruffalo into the picture to replace Edward Norton, and it looks like that plot thread got left behind.
The Thor franchise tried very hard to make a love story between Thor Odinson and Jane Foster work during the early days of the Marvel Cinematic Universe. Jane debuted in the original Thor movie, and then journeyed to Asgard during the events of Thor: The Dark World, but long distance finally got to them by the time Thor: Ragnarok rolled around in 2017. Thor and Jane have broken up, and the increasingly cosmic nature of the God of Thunder seems to suggest that Marvel has no intention of bringing her back anytime soon, even with Natalie Portman's remarks that she would be willing to return to the character.
The Ten Rings
The Marvel Cinematic Universe is almost unrecognizable compared to what it was in 2008, and certain villainous entities no longer have nearly as much relevance as they once did. Chief among these organizations is The Ten Rings, the group that kidnapped Tony Stark at the beginning of the original Iron Man movie. The multi-national terrorist organization has factored into the solo Iron Man movies as well as into the TV side of the Marvel Cinematic Universe, but lately, the armored Avenger has been dealing with more cosmic threats like Thanos and the Black Order. The Ten Rings has maintained radio silence for quite some time, and we don't expect to see them again anytime soon.
The Howling Commandos
Looking back, Captain America: The First Avenger is a particularly odd Marvel movie. It's a love letter to the Golden Age of comics, with a very distinctive visual style in the vein of cheesy serials. That's a framework that the Howling Commandos neatly fit into when the movie debuted, but it's hard to imagine a scenario in which a character like Dum Dum Dugan (Neal McDonough) fitting into what the Captain America franchise has become after the events of Captain America: The Winter Soldier. Like Cap's old life, there's a strong case to be made that this assortment of soldiers belongs in the past.
Oh, Trevor Slattery... Iron Man 3's fake out villain has handily become one of the most divisive plot elements of the entire Marvel Cinematic Universe, with Ben Kingsley's portrayal of the false Mandarin standing out as one of the most jarring scenes in MCU history. Some love him, and some hate him, and while there did seem to be a bigger plan for Trevor at some point, it looks like the folks over at Marvel Studios have opted to move on from that particular storyline. We know the real Mandarin is out there somewhere, but we definitely don't expect to see Trevor show up again anytime soon.
Shane Black's Iron Man 3 has become an incredibly divisive MCU movie for a number of reasons. That said, the relationship between Tony Stark and Ty Simpkins' Harley Keener stands out as one of the best elements in the entire movie. The brilliant-but-lonely child of a single mother turns out to be a vital sidekick for Tony in his hour of need, and the movie ends with the implication that Tony uses his fortune to help foster the boy's intellect. However, now that Peter Parker (Tom Holland) is in the Marvel Cinematic Universe, he more or less has taken the role that role from Harley.
Unlike a lot of characters on this list, Erik Selvig has specifically involved himself in the adventures of the fully-assembled Avengers team over the course of the last few movies, and it's easy to see why. Stellan Skarsgård's MCU character is a brilliant scientist and knowledgeable of Norse mythology, which makes him an incredibly valuable asset whenever Thor comes to town. Nevertheless, we haven't seen Selvig in any notable capacity since his journey to the Water of Sights with the mighty Avenger in 2015's Avengers: Age of Ultron, and there's no evidence to suggest that he may come back anytime soon.