At this point, nearly all the legacy characters in Marvel Comics have been spotlighted in feature films or TV shows, and still, the Marvel Universe houses multitudes of popular characters who might yet make their way to live-action cinema. The Marvel Cinematic Universe, alongside its Fox and Sony counterparts, has generated successful films for the Avengers, the X-Men, and the various Spider-People, with an ever-expanding schedule of spinoffs and reboots. However, there remain many beloved characters from the Marvel library who could carry their own movie; some have only been glimpsed in a live-action setting, some have not been heard from at all.
The point being, Marvel Comics runs deep, as in a basketball squad's deep bench of infinite reserves. Every character is the favorite of some fans, somewhere. Some characters are tied up in legal wrangling. Some are villains. Some are easily confused with other fictional personas. But as Guardians of the Galaxy more or less proved, even the obscure super-people can make for a broadly enjoyable movie. Here are a few Marvel creations who could take center in their own stories on the big screen:
Galactus
Galactus is a cosmic villain (sometimes anti-hero), an apocalyptic icon, and an eternally SEO-friendly search term. His motivation for eating planets stems both from personal hunger and a greater mission to balance the universe. His antagonists are "celestial" titans even taller than himself, as well as the human-sized Marvel denizens. His stoic, lonely odyssey could discover any number of alien civilizations before approaching Earth as a potential cliffhanger. Advancements in visual effects technology and artistry ought to be able to overcome the big guy's somewhat odd portrayal in 2007's Fantastic Four: Rise of the Silver Surfer.
Dazzler
The MCU hasn't truly made a musical yet, although the mutant pop star Dazzler has made cameo appearances in two X-Men films. Alison Blaire embodies a musician's journey, celebrity drama, a visually-thrilling superpower enabling lasers and holograms, and a variety of fabulous costumes. A Hailee Steinfeld kind of role, perhaps. Although a series with Tigra & Dazzler is/was a perfectly good idea, a feature-length musical tracking Dazzler's stylistic evolution from disco to synth-pop to stripped-down acoustic renditions of previous hits while lasing Sentinels in every era could be a great idea.
Karma
The much-delayed New Mutants film seems to lack Karma, arguably the founding member of the New Mutants. Karma's empathic-possession power would lend itself to a mind-control power-dynamic psychodrama in the vein of Jessica Jones Season 1. She is Vietnamese-American, queer, and navigated one of the most bizarre body-dysmorphia storylines in Marvel Comics history.
Miles Morales
This one presents a bit of a titling problem, but perhaps audiences will adapt. Miles Morales/Spider-Man assembled a diverse team of Spider-Folk in Into The Spider-Verse, and seems a likely candidate to launch into a solo film, given his enduring popularity with the fan base. More importantly, Into The Spider-Verse demonstrated that overlapping origins of identically-named Spider-Men can serve as a premise for comedy and solidarity, rather than confusion.
White Tiger
A nocturnal street fighter in the vein of Black Panther and Daredevil, White Tiger is also one of Marvel's relatively few Latinx superheroes (along with Mr. Morales, above). A lineage of Nuyorican men and women have used the identity (as have others, but the Puerto Rican White Tigers are probably the best-known versions). The conceptual similarities to Black Panther might present a few costuming/naming challenges, but no more so than the Avengers movie with Ant-Man, Spider-Man, Black Widow and Black Panther in it.
Silk
Silk, a.k.a. Cindy Moon, is the Asian-American Spider-Person whose origin involved many years of Oldboy-esque social isolation. She is just one of the characters in the appropriately tangled web of Sony Pictures' Spider-Verse projects which are in some unclear stage of development under producer Amy Pascal. If a) films like Venom and Morbius proceed apace and b) Spider-Man himself stays in a legal grey area wherein he doesn't quite appear in films featuring his traditional villains, there would seem to be a convenient space for Silk to emerge. She is the main arachnid hero who doesn't have "Spider" in her name, and someone's got to face that Sinister Six once they've all been introduced.
X-23
Dafne Keen literally killed as X-23 in the Logan film, which gave us an artfully-conceived variation on Laura Kinney's comics story. Any casual fan can observe that Wolverine-related material is always an exciting event, and Logan's director James Mangold has mentioned an interest in a Laura-centered spinoff. Like Logan, X-23 works with less of the comic-book baggage of costume, codename, and mythology; a young woman with unbreakable claws and berzerker tendencies is all the premise a movie needs.
Invisible Woman
If a new Invisible Man movie exists, why not reorient Fantastic Four mythology a bit to center on their most powerful member? Susan Storm's array of force fields and light-bending abilities make her the most cinematically interesting hero in Marvel's first family, the relatively one-note Human Torch notwithstanding. Telling the relational story of the Fantastic Four has always been a little awkward, and might benefit from taking one person's strong perspective.
Ironheart
Why not start at the beginning, again? As Iron Man effectively birthed the phenomenon we now call the Marvel Cinematic Universe, Riri Williams a.k.a. Ironheart could enter the post-Endgame era as the new bearer of the iron armor iconography. Fans are going to miss someone wearing that red-and-gold suit, but that someone doesn't have to be Tony Stark, and with all due respect to Pepper and Rhodey, Ironheart identifies the idea with a lot more clarity than Rescue or War Machine.
Honorary mention should be made for any character from the Canadian super-team Alpha Flight, thus far curiously absent from the live-action universe. In the near while, Marvel will roll out solo films/shows featuring Shang-Chi, She-Hulk, and Moon Knight, among others. Even if there were never another numbered sequel to any existing Marvel movie, the endless variations of characters permit a virtually inexhaustible field of self-contained yet interconnected stories. The proposals above represent only a small sample of future possibilities.