The Eternals may be the future of the Marvel Cinematic Universe. With Avengers 4 expected to serve as the final chapter for several heroes, the addition of a new franchise rumored to be in development will hopefully refresh the MCU with new characters and storylines for years to come.

Created by the legendary Jack Kirby, the Eternals are a race of super-powered immortals genetically engineered by space gods known as the Celestials. The Eternals dwell in many places in the Marvel Universe, including Earth. Some of the Eternals have even become Avengers.

Related: Marvel After Avengers 4: Everything We Know About MCU Phase 4

Rumors of Marvel Studios working on an Eternals film began to pick up steam back in April. Matthew and Ryan Firpo, two rising names in Hollywood, have been hired to pen the script. According to Marvel Studios head Kevin Feige, The Eternals could explore the history of the MCU. Their presence was briefly hinted at in Avengers: Infinity War with the mention of Thanos' father, A'lars.

Due to the Eternals' deep connections to Thanos as well as other aspects of the MCU, they could fit perfectly into Phase 4, introducing a number of interesting characters that could take on important roles in the MCU.

Ikaris

Eternals ikaris

Over the years, the Eternals have starred in numerous comic book titles, and have been featured as guest-stars in other comics, such as The Avengers, Iron Man,  and Thor. Always at the lead of the Eternals is Ikaris. In stories strictly about the Eternals, Ikaris is generally the main character. While the MCU doesn't necessarily have to follow in the footsteps of the comics, it's hard to imagine that an Eternals movie would ignore Ikaris.

The other Eternals look to Ikaris in the same way that Asgardians view Thor. Though Odin is the ruler of Asgard, it's Thor who they expect to fight their enemies. The same is true with Ikaris. When the Eternals are threatened, it's always up to Ikaris to save them. In the first Eternals story—which could end up as the plot of the film—Ikaris spent thousands of years preparing for the arrival of the Celestials, who he knew would come to Earth to pass judgment on their creations.

Related: New Characters Marvel Is Developing For After Avengers 4

As Ikaris is mainly recognized just as "the hero" of the Eternals series whose only goal is to save the day, fans can expect an Eternals movie to add extra layers to the character. If Ikaris does serve as the film's protagonist, he could very well become the face of the Eternals franchise, just like Iron Man was for The Avengers, potentially making Ikaris one of Phase 4's most important characters.

Ransak the Reject & Karkas

When the Celestials created the Eternals, they also created the Deviants, a genetic offshoot of the Eternals who look less like humans and more like monsters. Unlike the Eternals, the Deviants are able to blend in with humankind and are forced to live underground. Most Deviants are considered enemies of the Eternals, but two, in particular, are counted as friends. Karkas and Ransak the Reject are an interesting pair who are part of the core group of characters in the Eternals comics.

Treated as outcasts, the two are constant companions, despite being polar opposites. The wise and extremely articulate Karkas is a large, imposing, red monster with the "soul of a poet". Ransak is a savage fighter with a genetic defect. Ransak has the physical appearance of a human, so he is shunned by his fellow Deviants, but is considered to be attractive by Eternal—and human—females.

The unlikely friendship between Karkas and Ransak has produced many fun moments in the comics. Could the two Deviants be the MCU's next fan-favorite bromance?

Page 2: Starfox, Gilgamesh, and Sersi

Starfox smiling fwhile fliying in space in Marvel Avengers

Starfox

Not all Eternals dwell on Earth. Some originate from other parts of the cosmos. Another group of Eternals resided on Titan, one of Saturn's moons. In the comics, and the MCU, this was the birthplace of Thanos and his brother, Eros. Eros doesn't share his brother's monstrous appearance, due to the fact that Thanos has the Deviant gene and Eros is a pure Eternal. Eros has the ability to control the brain's pleasure center, allowing him to make people happy or sad. He can also use this power to make people like him.

Eros is a carefree wanderer who likes to get the most out of life by adventuring and womanizing. His pursuit of adventure is what led him to join the Avengers in the 1980s, where he took the name "Starfox" at the suggestion of the Wasp.

Related: Marvel Just Killed Off The MCU's Next Big Franchise

Starfox's power made him an interesting addition to the team. Being able to influence emotions made the female members of the group nervous around him. Many Marvel characters are unable to trust Starfox due to his powers, even though Starfox swears he never uses them for personal reasons.

It's not clear how a character like Starfox would be received in the MCU, but his powers aren't the only thing that would affect how others view him. Being the brother of the man who destroyed half of the universe could make people even more wary of him.

Considering his connection to the Mad Titan, no member of the Eternals is more relevant to the MCU right now than Starfox. In fact, if more of Thanos' backstory is revealed in Avengers 4, we could meet Starfox before Phase 4 even begins.

Gilgamesh

Gilgamesh The Forgotten One Joins The Avengers

The Eternals follow a strict rule that forbids them from interfering in the matters of mortals, but one character had a tendency to break that rule. After performing acts of heroism in the world of humans, he was exiled from his homeland forever, and it became a crime to even speak his name. As his true name has never been revealed, he has taken on a number of identities in his later travels, including "Hero", "The Forgotten One", and "Gilgamesh".

Related: How The Eternals Can Fit Into Avengers 4

As "Gilgamesh", he served as a member of the Avengers for a short time. As the strongest Eternal, Gilgamesh is seen as an equal to Thor when it comes to raw power. The name "Forgotten One" also has a more literal meaning. A curse causes all who cross paths with Gilgamesh to forget him soon after meeting him, forcing him to live a life of solitude.

Gilgamesh is easily the most tragic, and saddest character among the Eternals. He's the kind of character audiences may find it easy to root for. The story of Gilgamesh may even have the potential for a standalone movie, if The Eternals prove to be successful.

Sersi

For the most part, Ikaris and most of his fellow Eternals usually stay in their corner of the Marvel Universe, and only appear in other characters' titles on rare occasions. Perhaps the biggest exception to this rule is Sersi, a fun-loving party girl with the ability to manipulate matter on a grand scale.

Sersi is one of the only Eternals to spend so much of their time with other Marvel characters. Sersi joined the Avengers in the early 1990s, and brought a lot of tension and funny moments to the team. Sersi enjoyed flirting with Captain America, as she knew it made him uncomfortable. She often used her matter-manipulating abilities to have fun or get payback on those she didn't like.

Related: Marvel Studios Really Is Holding Back Phase 4 Titles Until Avengers 4

Sersi is arguably the Avengers' most powerful—and most dangerous—member. In a lot of ways, she was the Avengers' equivalent of the X-Men hero, Jean Grey, who could transform into the Dark Phoenix. For a time, the Avengers had to deal with the possibility of Sersi losing control. She had to form a mystical bond with Black Knight in an effort to maintain her sanity. Her potential for destruction made her an extremely divisive character, which even resulted in a conflict between the Avengers and the Eternals.

As of now, the MCU doesn't have a character remotely like Sersi, so adding her to The Eternals film could be a great thing for the MCU, especially since it would open up plenty of options in terms of story-telling.

More: How Avengers 4 Can Add X-Men To The MCU Retroactively

Key Release Dates