The Marvel Cinematic Universe (MCU) is about to welcome one of its most complex and powerful superheroes onto the big screen—The Sentry. Marvel has introduced countless superheroes over the years, but few are as mysterious and powerful as Sentry. If you’re unfamiliar with The Sentry, there’s a good reason. Despite possessing god-like abilities, he remains largely forgotten—both in the Marvel Universe and among fans. This isn’t just a matter of popularity; Sentry’s very existence was intentionally erased from history.
Now, that’s about to change. Sentry is set to make his live-action debut in the upcoming Thunderbolts* movie, and if Marvel stays true to his comic origins, he could become one of the most important characters in the MCU. But who is Sentry, and why is his story so unique?
Here’s everything you need to know about The Sentry—his origin, powers, struggles, and why he may become the MCU’s next pivotal figure.
Who Is Robert Reynolds?
At first glance, Robert “Bob” Reynolds seems like an ordinary man. He lives a quiet life with his wife, Lindy, and appears to be just another average citizen. However, beneath the surface, Bob is plagued by something he cannot explain—vivid dreams and fragmented memories of a life that feels more real than his own.
In these visions, he sees himself as Sentry, a hero with unimaginable power who once fought alongside the Avengers and Fantastic Four. Yet, no one around him seems to remember this version of him—not even the heroes he once called allies.
As Bob grapples with his confusion, he stumbles upon a book on his shelf. Inside, hidden within its pages, he finds a small bottle. The sight of it triggers something deep within him, unlocking memories of an event that would change his life forever.
The Birth of Sentry
Bob’s memories take him back to the 1960s when a secret government project was developing an advanced version of the Super Soldier Serum—the same formula that transformed Steve Rogers into Captain America. However, this new serum was vastly more powerful, capable of granting unimaginable strength to whoever consumed it.
Desperate and unaware of what he was about to do, Bob broke into a laboratory and drank the serum. In an instant, his body underwent a transformation beyond anything science had ever seen. He became Sentry—a being with the power of a million exploding suns.
With his newfound abilities, Bob dedicated himself to heroism. He became the first true superhero of the Marvel Universe, long before the Avengers formed. He fought alongside legends like Spider-Man, Hulk, Fantastic Four, and the X-Men, taking on threats that no other hero could face.
Yet, despite his greatness, something about Sentry didn’t add up. His memories were fragmented, and a dark presence seemed to lurk in the shadows of his mind.
Who is the Void
For every force of light, there is an opposing darkness, and for Sentry, that darkness took the form of Void. Unlike traditional villains, Void was not a separate being—it was the physical manifestation of Sentry’s own dark side.
Whenever Sentry used his powers, Void grew stronger. It was as if the universe had balanced Sentry’s overwhelming goodness with an equally destructive evil. Void was ruthless, wreaking havoc across the world, murdering countless people, and even threatening entire civilizations.
Sentry and Void were inseparable—two sides of the same coin. The more Sentry fought to protect the world, the stronger Void became. It was a battle that had no clear winner, and eventually, the heroes of Earth realized something terrifying: as long as Sentry existed, Void would too.
Erasing Sentry from History
Faced with an impossible dilemma, Marvel’s greatest minds—Reed Richards (Mr. Fantastic), Doctor Strange, and Professor X—came to a painful conclusion: the only way to stop Void was to erase Sentry from existence.
Using a specially designed memory-blocking transmitter, they wiped all knowledge of Sentry from the minds of every person on Earth, including Bob himself. His greatest battles, his victories, his friendships—all of it disappeared in an instant. The world had lost its greatest hero, and in doing so, it had also rid itself of its most terrifying enemy.
To ensure that Sentry could never return, his Watchtower, the massive headquarters that once stood in the heart of New York City, was hidden from reality. It still existed, but no one could perceive it—not even Bob.
With no memory of his past, Bob Reynolds returned to a normal life. He lived peacefully, unaware of the power that once coursed through him. But the past never stays buried forever, and eventually, Sentry would return… bringing the Void with him.
The Return of Sentry
For years, Robert Reynolds lived an unremarkable life, blissfully unaware of his past as Sentry. However, his peaceful existence came to an abrupt end when memories of his forgotten identity began to resurface. It started subtly—strange dreams, flashes of battles he didn’t remember fighting, and an overwhelming sense that something was terribly wrong.
One night, unable to shake the feeling that he was missing something important, Bob stumbled upon an old book on his shelf. Hidden inside was a small bottle—something that felt strangely familiar. As he looked at it, his fragmented memories rushed back. He wasn’t just Bob Reynolds; he was Sentry.
Desperate for answers, Bob sought out Reed Richards, one of the smartest men in the world and someone he vaguely remembered as an old friend. But when he confronted Reed, the scientist had no idea who he was. Frustrated, Bob tried to jog his memory by mentioning an unusual event—a wedding where they had once seen a unicorn. Reed dismissed him at first, but later, when he casually brought up the memory with Sue Storm, something extraordinary happened.
A golden unicorn suddenly materialized before them. It had always been there, but their minds had been altered to prevent them from perceiving it. This moment triggered a hidden videotape that Reed had unknowingly stored away. When he played it, he saw something shocking: a past version of himself warning that if Bob Reynolds ever returned, they should never try to remember who he was. The message also confirmed their worst fear—Sentry’s return meant Void was returning too.
Meanwhile, Bob sought out Bruce Banner, hoping that the Hulk might remember him. Unlike Reed, Hulk did remember. Since Bruce Banner and Hulk are two separate identities, the memory-erasing process had only affected Bruce. Hulk, however, never forgot his old friend. Bob warned him that Void was coming back, which even made the Hulk uneasy. To help him, Sentry gave Hulk a small piece of the sun, telling him it would protect him if needed.
As more heroes began piecing together fragments of their forgotten memories, Bob realized that the truth had been deliberately hidden. He needed to uncover the full story.
Sentry vs. Void
The moment Bob fully embraced his identity as Sentry, his Watchtower—which had been invisible to him for years—suddenly appeared before him. Entering the tower, he activated an AI system, which instantly recognized him and began answering his questions.
Sentry asked why no one remembered him, and the AI revealed the shocking truth: a powerful transmitter had been sending out signals for years, keeping everyone’s memories of Sentry suppressed. Worse yet, Sentry himself had been the one who activated it.
Horrified, Bob realized that the transmitter had prevented the world from remembering him—but also from remembering Void. If he destroyed the machine, everyone would remember Sentry, but that also meant Void would return. Despite this risk, Bob decided he needed to know the truth. He destroyed the transmitter, unleashing a powerful shockwave across the city.
Instantly, everyone remembered Sentry. His old comic books, action figures, and posters reappeared. Even his wife, Lindy, finally recalled who her husband truly was. But along with these memories came a terrifying realization:
Void had returned.
Just as Bob was reuniting with Lindy, Void appeared out of the shadows and attacked. In a horrifying display of power, Void grabbed Lindy and threw her from the Watchtower. Sentry raced against time, catching her just before she hit the ground. Then, looking down at the city, he saw a storm of darkness spreading—the unmistakable sign that Void was here to finish what he started.
Sentry knew this battle was too big for him alone. He called upon the Avengers and all of Earth’s mightiest heroes, warning them that Void had returned, and this time, he might be unstoppable.
As the battle raged, the Avengers, Fantastic Four, X-Men, and even Hulk fought against Void, but their attacks barely made a difference. Void was stronger than ever, feeding off Sentry’s own power.
Sentry fought with everything he had, but he began to realize the truth: Void couldn’t be defeated because he and Void were one and the same.
The Heartbreaking Sacrifice
During the battle, Doctor Strange intervened and urged Reed Richards to remember why they had erased Sentry in the first place. Reed, still struggling to understand his past choices, suddenly experienced a memory breakthrough. He recalled the previous battle with Void, where all of Earth’s heroes had tried to stop him—and failed.
The only solution they had found was that Void was a subconscious manifestation of Sentry’s own mind. As long as Sentry existed, Void would always return.
Realizing this, Sentry made the ultimate sacrifice. He asked Reed and Doctor Strange to reinstall the transmitter, wiping his existence from the world once again. He understood that the only way to save the world was to erase himself completely—forever.
Void, knowing what was about to happen, tried to stop them. But this time, Sentry ignored him. With the help of Reed and Strange, the transmitter was reactivated.
As the machine pulsed, Sentry and Void disappeared together. Once again, the world forgot about Marvel’s most powerful hero. The destruction left by their battle was dismissed as nothing more than a freak storm by the media.
In the final moments, Robert Reynolds, now just an ordinary man once more, was seen sitting with his wife in their car, listening to the news. He had no memory of ever being a hero, and for the world, Sentry had never existed.
Conclusion
Sentry’s story is one of tragedy and sacrifice. Despite being one of the most powerful beings in the Marvel Universe, he remains the most forgotten. His dual existence as both a hero and a villain made him an unstable force, and ultimately, the only way to stop the darkness inside him was to erase himself completely.
However, in the Marvel Universe, nothing stays buried forever. With Sentry making his live-action debut in the MCU’s Thunderbolts* movie, fans are left wondering:
Will Sentry return? And if he does, will Void follow?
Only time will tell if Marvel’s forgotten hero will once again step into the light—or if the darkness will consume him once more.
