Marvel's will be Nick Fury and the Skrull leader Talos, and there have been a couple of other casting rumors to round out the actors involved.
Emilia Clarke, Olivia Colman, and Kingsley Ben-Adir are all said to have a part in Secret Invasion. With the series likely looking very different from what fans have come to expect from the comic book event, there's no telling who these talented performers may be portraying. However, there are certainly several potential options as to who they might be inhabiting the life of on-screen.
Emilia Clarke: Veranke
Veranke is perhaps one of the most vital characters in the Secret Invasion narrative and the most likely contender for who Emilia Clarke might be portraying. The Skrull Queen is one of the masterminds behind the attack plan, and is both powerful and manipulative.
Taking on the form of Spider-Woman for a great deal of the character's career, Veranke was one of the Skrull agents, who created chaos before the species' eventual rise. Emilia Clarke certainly has the range to take on this complex character, who rose to glory through the ranks and was eventually defeated by Norman Osborn, who was the Thunderbolts director.
Kingsley Ben-Adir: Kly'bn
Kingsley Ben-Adir is a talented actor in his own right and certainly brings with him a great deal of range, which means he could really take on a number of huge roles from the comic books. However, for the purposes of Secret Invasion, Kly'bn could be a potential fit.
Not only does the character have a big role in the narrative, but also could be a part of the MCU long-term. Kly'bn is the Skrull God that the species worship and, as a deity of sorts, is extremely powerful and considered to be an Eternal (which is a group who will also be making their impact felt in the Marvel universe).
Olivia Colman: Victoria Hand
Victoria Hand has actually made an appearance in the Marvel Cinematic Universe already in Agents Of S.H.I.E.L.D. She met her untimely demise thanks to Hydra, although would later make a reappearance on an alternate Earth. With timeline changes and some retconning, it's easy to imagine Marvel bringing back Hand in a different form.
Victoria Hand is heavily entrenched in S.H.I.E.L.D. in the comics and later goes on to work for Norman Osborn and H.A.M.M.E.R. She plays her part in the war against the Skrulls and it's a good fit for Olivia Colman to take on this morally gray role, as Hand politics her way into power.
Emilia Clarke: Abigail Brand
Strangely enough, Abigail Brand has yet to be used in the MCU thus far; neither in S.H.I.E.L.D. nor any of the space-based franchises. As the leader of S.W.O.R.D. Brand is one of the most dedicated heroes to fighting off any galactic threats, which could pose a problem for Earth.
With S.W.O.R.D. introduced into the MCU through WandaVision and Nick Fury potentially a part of their space division, it's possible that Emilia Clarke could be brought in as a long-term player. Abigail Brand is also of both Mutant and Alien origins.
Kingsley Ben-Adir: Titannus
Titannus is one of the most powerful Skrull villains in the comics. Shunned by his people and experimented on, he's almost like the Super Soldier of his people. He would later travel through the galaxy, finding new planets to dominate and building himself an Empire.
He does not have a major role to play in the Secret Invasion story in the comics, but could certainly be brought in here as a threat to both Earth and the pre-existing MCU Skrull Empire. It would take someone like Ben-Adir to portray the many layers of this notable Skrull.
Olivia Colman: Princess Anelle
Princess Anelle was a significant member of the Skrulls for quite some time. Her death was tragic but her legacy is the most intriguing part of her character. After falling in love with the Kree Mar-Vell, she broke down barriers amongst her people with who The Empire was at war with.
The two would later have a son, Hulking, who would the Young Avengers and eventually become the key to trying to restore order in the galaxy. Her role in the Skrull narrative is completely irreplaceable and it would be compelling to see Colman take on such a vital character in the species' history.
Emilia Clarke: Lyja
Lyja is one of the few Skrulls that defected from her people and actually sided with humanity during the Skrull invasion. She is often linked to the Fantastic Four, who could also find themselves included in Secret Invasion. She was even married to Johnny Storm once upon a time.
She directly disobeyed orders during the Secret Invasion after being told to destroy the Baxter Building. She has fought on both the side of good and evil but has redeemed herself countless times, and for the most part, is looking for a quiet life. Lyja could be part of the next wave of Skrull heroes on the screen under the guidance of Emilia Clarke.
Kingsley Ben-Adir: Z'Reg
Z'Reg could be the most perfect fit for Kingsley Ben-Adir's talents. The Skrull found himself on an Earth-based mission early into his life. However, coming across as the hero, known as Crusader, he began to become attached to humanity and decided to assimilate into Earth.
Once his friend and mentor died, he took on the role of the Crusader. He ed the Avengers Initiative and during the Secret Invasion, he actually fought back against the Skrulls. Unfortunately, he was mistaken for a sleeper agent and murdered by 3-D Man. Ben-Adir would portray both Z'Reg and Crusader brilliantly.
Olivia Colman: Empress Dorrek VII
In the comics, Emperor Dorrek VII is one of the most powerful Skrulls in the species' hierarchy. Corrupt and bloodthirsty, strangely enough, the character is actually the nephew to Talos and father to Anelle; a vital part of the Royal Family. He's one of the masterminds behind the Kree and Skrull war.
While his death occurred before the invasion of Earth, he did begin to sow the seeds of its destruction. A gender change would see Olivia Colman as the Empress, perhaps leading the invasion herself or setting up Veranke in a mentorship capacity.
Ben Mendelsohn: The Untamed
Thus far, Talos has been partially positioned as comic relief. He has been considered to be one of the 'good' Skrulls and has earned the trust of Nick Fury. Yet, a major plot twist could be on its way, which may reveal a much darker figure inside of Talos.
In the comics, Talos is known as The Untamed for some time before transitioning into The Tamer. It's possible that Secret Invasion could seal his fate and see Ben Mendelsohn inhabiting a different, more villainous personality; maybe one repressed by sleeper agent technology or triggered by a significant event.