Many of these Hulks are worthy of MCU debuts and with She-Hulk officially joining the universe, it is safe to say many more Hulks will be debuting in the MCU timeline very soon, some of which have already been teased previously in past movies.
Michael Steel, later known as Iron Clad, is a Hulk-like villain who has a metallic exterior and possesses super-human strength (alongside the power of density manipulation). Steel was an engineer, scientist, and pilot who recreated the original rocket flight of the Fantastic Four through a cosmic ray belt in order to grant him superpowers.
His experiment was successful and Steel then used his superpowers for evil, battling the likes of Daredevil, Captain America, and primarily, The Hulk. Iron Clad has been a reoccurring villain in many forms of media and is worthy of at least a cameo in She-Hulk: Attorney at Law or a feature in Thunderbolts when he finally makes his MCU debut.
Weapon H is the Hulk form of ex-mercenary, Clayton Cortez, who was forcibly infused with both Amadeus Cho and Old Man Logan's DNA whilst in the Weapon X program, turning him into a grey hulk with retractable adamantium claws. With the character interacting with the likes of MCU characters, such as Doctor Strange, Hulk, and Black Knight in the comics, he may be a perfect fit for the MCU.
After Disney had gained the acquisition of Fox and all of the X-Men film rights (via Vox), Marvel has the opportunity to debut not only Wolverine but also Weapon H within the cinematic universe (possibly as the main antagonist of Mark Ruffalo's dream 'Hulk vs Wolverine' movie, with the character being a common enemy for both Hulk and Wolverine in the comics).
Leonard Skivorski was the former psychiatrist of Bruce Banner, who was exposed to gamma radiation (which granted him superhuman strength and physique). Samson is affiliated with many pre-existing MCU characters, including Bruce Banner's former partner Betty Ross, which sparked an intense rivalry between Samson and The Hulk.
Skivorksi has appeared in the MCU previously in The Incredible Hulk (and was portrayed by Ty Burrell), but, unfortunately, the character did not transform into his Hulk form and has not appeared in the MCU since. However, after the likes of Tim Roth's Abomination appearing in Shang-Chi and the Legend of The Ten Rings and She-Hulk, it isn't completely far-fetched to expect a return from Burrell and Samson soon, potentially in a future season of the show.
Skaar is the son of The Hulk, who was conceived in the comics during The Hulk's time on Sakaar (the home planet of Skaar's mother Caiera). Although Skaar hasn't appeared in the MCU yet, there is a chance he could have been conceived during The Hulk's time on Sakarr in the MCU. Alongside this, the character has ties to the multiverse in certain storylines, so there is always the opportunity to debut the character via the multiverse.
There is a lot of potential for Skaar in the cinematic universe as he is often portrayed as an anti-hero or villain, meaning he could be the destructive, murderous Hulk Bruce Banner never has been within the confines of the MCU. Skaar may appear in a future Hulk project, such as She-Hulk, where he could work with Jennifer and Bruce to battle a greater evil or ally with a villain, such as The Leader, later joining a team like The Dark Avengers.
Hulkling is a Skrull/Kree hybrid who not only has the power of super-strength but also possesses the unique abilities of both flight and shape-shifting. An empowering role model for the LGBTQ+ community, he is currently in a loving relationship with The Mutant Wiccan.
As the MCU is clearly building up to a Young Avengers project, even copywriting the title Avengers Academy and debuting members, such as Wiccan, it is likely that Hulking will appear in the universe soon. Plus, with the Kree and Skrulls both being MCU canon and with Secret Invasion (a Skrull-centered project) alongside She-Hulk right around the corner, it seems The MCU is preparing for an imminent Hulkling debut very soon.
When in the form of The Red Hulk, Thunderbolt Ross is granted abilities, such as super strength and the ability to overheat to extreme temperatures (which he often uses when battling his nemesis The Hulk). Thunderbolt Ross debuted in The Incredible Hulk (portrayed by William Hurt) and has been an integral part of the MCU since, appearing in 5 movies overall.
The Red Hulk has yet to appear in the MCU and after William Hurt's unfortunate passing, it's likely that the character won't be appearing in a project anytime soon. However, there is still a chance that there could be a reference to him or some sort of variant.
Amadeus Cho was a former partner of Bruce Banner and eventual successor to The Hulk after transforming into his Hulk form Brawn. Unlike Bruce, Amadeus has no problem controlling his power and Hulk form due to his confidence and genius-level intellect.
Helen Cho, Amadeus' mother, appeared in Avengers: Age of Ultron, working closely with Bruce Banner and impressing him with her tremendous knowledge and unmatched understanding in the fields of cell biology. Due to Helen existing within the MCU timeline and her affiliations with Bruce Banner, the seeds have already been sown for Amadeus to debut within the MCU, possibly in a later season of She-Hulk or his own solo project.
The daughter of Thunderbolt Ross, Betty Ross, was mysteriously resurrected as The Red She-Hulk after her death (an evil version of She-Hulk with superhuman strength and other superhuman abilities). Although she has never transformed into her Hulk form on-screen, Betty Ross did appear in The Incredible Hulk (portrayed by Liv Tyler) but hasn't appeared since.
With the return of love interests, such as Jane Foster and Christine Palmer, in Phase 4, the chances of Tyler reprising the role of Betty are high. After William Hurt's passing, many doors have been opened for Betty Ross to return to the MCU, possibly as Marvel's main Red Hulk to fill the void left by Thunderbolt Ross' absence (and passing Banner and Ross' iconic rivalry onto Jennifer Walters and Betty Ross, possibly in a future season of She-Hulk).
Rick Jones is the sidekick of Bruce Banner who was given the ability to turn into A-Bomb, a blue Hulk form, after a gamma bomb explosion. When in his hulk form, Rick is granted super-strength and energy projection, having varying degrees of control over his Hulk form depending on the storyline.
An easter egg in The Incredible Hulk confirms the existence of a student named Richard 'Rick' Jones in the MCU and in Avengers, another easter egg can be seen suggesting Banner had previously saved Rick Jones by throwing him into a trench near a gamma bomb explosion, which is exactly the same as A-Bomb's origin in the comics. With Hulk-centered projects like She-Hulk releasing soon coupled with these previous easter eggs, it may be possible that A-Bomb will debut in the MCU soon, in his hulk or human form.
Samuel Sterns was transformed into The Leader after he was bombarded with gamma radiation, causing his head to grow and granting him a genius-level intellect (with an inflated ego and an intense sense of ambition to match). This gamma-infused villain is the self-proclaimed arch-enemy of The Hulk and has battled many heroes since his debut.
Samuel Sterns appeared in The Incredible Hulk (portrayed by Tim Blake Nelson). In Stern's final scene on-screen, Banner's gamma-infused blood dripped into a cut on Samuel's head, leading to his head changing shape and growing in size, teasing The Leader's MCU debut. Sterns hasn't reappeared in live-action since but Kevin Fiege has expressed interest in seeing Sterns return, meaning The Leader could eventually debut in She-Hulk or the Thunderbolts project.