Who Is Sentry (and The Void) from Marvel Comics?

Have you ever felt torn between two sides of your personality? Maybe one side is a little more mischievous than your regular do-gooder habits. Perhaps you have a secret urge to do the unexpected — like destroy the universe. Too far? Probably for the average person, but not for Marvel Comics’ Robert Reynolds, AKA Sentry.

The Sentry, and his ultra-evil alter ego The Void, will appear in Thunderbolts*. This next MCU adventure is set to premiere on May 2, 2025. Ahead of the film’s debut, let’s uncover the tragic secrets of Robert Reynolds — and just how big a threat he poses to the heroes of Marvel. You’ll want him on your side. Or else.

---

Robert Reynolds Lives a Life Divided

What Is the First Appearance of Sentry in Marvel Comics?

Sentry first appeared in Sentry #1 (2000), written by Paul Jenkins with art by Jae Lee. There are differing origins surrounding Robert Reynolds and his reason for breaking into a secret laboratory. Some accounts say he was a troubled high school student, others a struggling drug addict looking for his next hit. The fact is that Reynolds got his hands on the Golden Sentry Serum. Like the Super Soldier Serum, this experiment sought to create super-powered individuals. It was developed by both Department K (the Canadian operation responsible for Wolverine) and Project: Rebirth (the American organization that created Captain America, Agent Venom, and others). Together, they formed Project Sentry.

Whereas Steve Rogers became an exemplary hero, Reynolds’ mental illness resulted in two powered-up personas: The Sentry and The Void. But, at first, he was simply The Sentry. Project Sentry recognized Reynolds’ danger and put safeguards in place to check his power. The Professor, whose lab Reynolds broke into, conditioned Reynolds to create self-imposed restrictions on his power, believing himself to be dependent on a serum that refills his power.

The Sentry Becomes a Marvel Super Hero

Reynolds, in his civilian life, married his high school sweetheart Lindy Lee. Professionally, Project Sentry reluctantly allowed him to become a super hero, since his newfound powers inspired him to help others as The Sentry. In truth, a large part of The Sentry’s success was his palatable appearance. He is blonde, conventionally handsome, and has a positive demeanor — all the makings of a classic hero.

However, he also forged close relationships with his peers. Though the public accepted him more willingly than mutants, mutates, and eccentrics, Sentry was a friend to the X-Men, Inhumans, and especially Spider-Man. Over time, his immense power levels meant he was constantly manipulated by those around him, often for selfish reasons or out of fear. Sentry became a member of the New Avengers because they worried his power could outmatch even Scarlet Witch. Later, Norman Osborn recruited Sentry to the Dark Avengers to be his powerhouse. Even Doctor Strange has used The Void’s nigh-omnipotence to defeat Loki, a crushing blow to Robert’s trust in the former Sorcerer Supreme.

---

What Are The Sentry’s Powers?

So everyone wants Sentry on their side, but why is that? Aside from his innate danger as the vessel of The Void, Sentry has a nearly endless list of abilities. And most of these abilities are untapped. Sentry has only scratched the surface of his potential — which is saying a lot.

Because the Golden Sentry Serum aimed to create super soldiers, The Sentry possesses the traditional roster of superhuman abilities: flight, strength, durability, stamina, invulnerability, along with enhanced intellect. He’s even the designer of his own headquarters, the Watchtower, and its AI system, CLOC. But that’s not all.

While all those abilities make Sentry a tough opponent, he can also manipulate matter, allowing him to shapeshift, affect the life force of others, and even resurrect himself and others. Basically he’s immortal. Not to mention he can wield light-based energy and tap into psionic abilities powerful enough to subdue the Hulk without lifting a finger. On a power scale, he’s been said to wield the power of “one million exploding suns.”

How Does The Void Work?

On his own, The Sentry would be enough of a danger to others. Mr. Fantastic even identified him as an Omega-Level Threat. Yet there’s a darker side to Sentry. Due to his fragile mental state, Reynolds cannot reconcile his three personas. And the concerning part is it’s not just a split personality situation. When The Void is present, it’s literally another entity.

It’s not known for sure whether The Void is an ancient evil force or a mental virus implanted by Sentry’s enemies. Whatever the source of The Void may be, it activated itself within Reynolds as soon as he took the serum. Not even Reynolds himself is sure who came first. In contrast to Sentry’s photokinetic abilities, The Void possesses umbrakinesis, weather manipulation, and the ability to possess others. Most famously, he uses shadowy tendrils to inflict excruciating physical and mental pain upon victims. The Void has vowed that for every person The Sentry saves, The Void will kill another.

---

Why Does No One Remember Sentry?

There’s no denying the immeasurable threat that Robert Reynolds presents. But one final question remains: Why does no one remember Sentry? Every step of the way, Reynolds faced internal conflict of world-ending proportions. An exhausting battle between Sentry vs Void raged within him. That’s how Sentry’s enemy, The General, managed to convince Sentry (with help from the mutant illusionist Mastermind) that he should cease to exist, for the safety of the world.

As Sentry realizes he’s fighting a losing battle against himself, he makes an interesting move. He gets in contact with a comic book writer to share his story. Once his history is out on the page, he’s ensuring there’s a blueprint for him to return to later. Enhanced intellect, remember? With that, The Sentry used his psionic power to make the entire world forget about his existence. Even his Watchtower faded from public perception, to be replaced by Tony Stark’s own hero headquarters. However, entities as formidable as The Sentry and The Void never stay repressed forever.

Allies & Enemies

Despite his overwhelming personas, Reynolds is extremely close with Spider-Man. He even deduced Spidey’s secret Peter Parker identity back in the day. Quite interesting considering both heroes, on the page and on the screen, have dealt with public perception mishaps. Sentry frequently collaborates with Doctor Strange and Reed Richards. Emma Frost has also proven to be a trusted ally to Sentry. He’s been a member of the New Avengers, the Mighty Avengers, and he once dated the Inhuman Crystal.

During the Civil War, Sentry sided with Iron Man. On the other hand, he’s a frenemy of sorts with the Hulk. With his brute strength, Sentry/Void has been known to rip opponents in half, including Ultron, Morgan Le Fay, and Ares. As Void, he became Death, a Horseman of Apocalypse, and he also merged with the Silver Surfer. Some have had (temporary) success against The Void — Thor and Knull managed to kill Void on separate occasions. But the most tragic ending of all was when Sentry took it upon himself to fly Void into the sun.

---

He has many names — the Golden Guardian, Life-in-Death, The Sentry, The Void, and finally, Robert Reynolds. How do you think Sentry and Void will factor into the MCU? And who (or what) are you most looking forward to in Thunderbolts*?

Join the conversation with other Marvel fans over at Sideshow Social Network or in side.show/geekgroup, and don’t forget to Let Your Geek Sideshow!