Who is Bob AKA The Sentry in Marvel's Thunderbolts*?

But we're getting ahead of ourselves. Who is Bob, and how does his superhero alter-ego factor into Thunderbolts*?

Read on if you'd like some insight into what to expect from this bold new addition to the Marvel Cinematic Universe.

Warning: Spoilers follow for Marvel's Thunderbolts*

Who is The Sentry in Marvel's Thunderbolts*?

The Sentry (also known by his civilian name Bob) is a comic book character introduced to the Marvel Cinematic Universe in team-up film Thunderbolts*.

The team first stumble upon Bob in the underground bunker they've been lured to by Julia Louis-Dreyfus's Val.

Though he initially appears clueless and unthreatening, making his presence at the top secret location a puzzling conundrum, his past is soon revealed – he suffers from severe mental health issues, has struggled with addiction, and was injected with the same serum that gave Captain America his powers.

Of course, the results were vastly different. Not only does he develop a superhero alter ego, The Sentry, but also a villain persona he can't seem to control, the Void.

Pullman spoke to RadioTimes.com about how the character's mental health was approached. "It's a hard topic, because you want to pay respect to the right terms that should be used when you're talking about stuff like this, but also, at the same time, you don't want to be scared of talking about it, scared of saying the wrong thing," he said.

"And that's what's so helpful about having a gang of misfits trying to discuss topics like these," he added. "It kind of sheds that strict nature around, like, if you say the wrong thing, then you're a bad person [and] you shouldn't talk about this kind of stuff anymore. Like, we should obviously take the time and educate ourselves about the right terminology, but also, at the same time, just not be hard on ourselves for failing and falling on the way there."

Though he ends up joining the Thunderbolts by the end of the movie, it's unlikely this is the last we'll see of the Void.

What is The Sentry's comic book origin?

Robert 'Bob' Reynolds is an addict suffering from various mental health issues, who comes across an experimental version of the super soldier serum after breaking into a secret laboratory.

Unlike in the film, where Bob is injected with the serum as part of Val's experimentation project, comic Bob consumes the content of the vial, hoping that it will give him some kind of high, but instead is transformed into a being of unimaginable power, or as his tongue-in-cheek tagline puts it: "The power of a million exploding suns."

This effectively makes The Sentry one of the most powerful – and dangerous – entities in the entire Marvel Universe, but these gifts come at a terrible price.

As Dr Erskine (Stanley Tucci) tells Steve Rogers in Captain America: The First Avenger, the super soldier serum enhances not only the user's physical attributes, but also their psychology and the way that they think about the world.

In the case of Bob Reynolds, his mental instability is heightened to such an extent that it makes him volatile, producing an opposing entity to The Sentry called The Void, which is the polar opposite of the Golden Guardian of Good in every way.

In Marvel canon, The Sentry was one of the first superheroes and was beloved around the world, rubbing shoulders with the universe's most prolific names – even serving as best man at the wedding of Reed Richards to Sue Storm.

However, when it became apparent that The Sentry and The Void were inextricably linked – and that the latter posed an existential threat to mankind – all were agreed that drastic action had to be taken.

Using futuristic technology emitted from atop The Sentry's watchtower – his base of operations – the superhero amplified a spell cast by Doctor Strange that would erase him from the memories of everyone from Earth.

Marvel Studios recently told a similar story in Spider-Man: No Way Home, although in that case Tom Holland's Peter Parker was the subject of the enchantment, removing him from the memories of MJ (Zendaya) and Ned (Jacob Batalon), among others.

The debut of The Sentry in a self-titled comic released in 2000 was accompanied by a hoax marketing campaign, in which Stan Lee claimed that the character was created by himself and a forgotten artist back in the 1960s.

Lee claimed that the ideas for the character were filed away and lost, only to be discovered decades later and repurposed by a modern day creative team comprised of writer Paul Jenkins and artist Jae Lee.

This was untrue; the character was an original invention of Jenkins and Lee, but the hoax was intended to draw a parallel between the character's in-universe backstory and his introduction to real-world comic book readers.

Is The Sentry the same person as The Void?

Yes, The Void and The Sentry are both aspects of Bob Reynolds's psyche, who are in a constant battle for control over his actions.

Where The Sentry is a benevolent figure similar to DC's Superman in terms of power and presentation, The Void is an entity of pure malice that wreaks death and destruction wherever it goes.

In one comic by the character's co-creator Paul Jenkins, it is explained that for every positive action The Sentry takes, The Void will counter it with an opposing negative action.

In the original The Sentry series, The Void carried out a brutal massacre of innocent civilians in New York City, but only Bob was present when the other Marvel heroes arrived on the scene.

Not long after, it became apparent that they were one and the same, with the logic of The Sentry's banishment being that so long as Bob cannot remember his heroic or villainous alter-egos, neither will pose a risk to the world at large.

Since then, the character has come and gone on numerous occasions, with his most prolific being between 2005 to 2010, when he was a member of the New Avengers and, subsequently, Norman Osborn's Dark Avengers.

As his mental state deteriorated over that five-year period, Osborn pressured and manipulated Bob into doing his bidding, which ultimately had disastrous consequences for all involved. That's why you don't trust Green Goblin to run the Avengers, folks.

The ongoing dynamic between The Sentry and The Void has often been read as an allegory for internal struggles with mental illness, such as depression, addiction and schizophrenia.

Who plays The Sentry in Marvel's Thunderbolts*?

The Sentry (aka Bob) is played by Lewis Pullman in Marvel's Thunderbolts*.

The son of Hollywood star Bill Pullman (star of Independence Day, The Equalizer and acclaimed crime drama The Sinner), he has embarked on an acting career of his own over the past decade.

Pullman's most notable credits thus far include Battle of the Sexes, Bad Times at the El Royale, Top Gun: Maverick and Salem's Lot. He has also appeared opposite fellow Marvel stars Josh Brolin and Brie Larson, in Prime Video's Outer Range and Apple TV's Lessons in Chemistry respectively.

The latter project earned him an Emmy Award nomination for Outstanding Supporting Actor in a Limited Series.

Earlier this year, Pullman was confirmed to be reprising his role as Bob Reynolds aka The Sentry in the upcoming blockbuster Avengers: Doomsday, which is currently filming for a cinema release in May 2026.

Previously, Invincible and Mickey 17 star Steven Yeun was attached to the role of The Sentry, but ultimately dropped out before filming commenced.

Marvel's Thunderbolts* was released in cinemas on Thursday 1st May 2025.

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