Marvels upcoming Thunderbolts movie will feature Lewis Pullman as Bob, aka The Sentry. But we also just found out via Marvel's big announcement video that Pullman is also joining the cast of what we can only assume is Avengers: Doomsday.So with this Superman-esque hero finally making his MCU debut, let's look at who The Sentry is and why he is both the Marvel Universes greatest hero and its worst nightmare. Read on for a breakdown of the history of this mentally unstable hero. These are the topics we cover here:Who Is Lewis Pullmans Thunderbolts Character The Sentry?The Sentrys Powers and AbilitiesThe Sentrys Secret OriginThe Sentry as an AvengerHow The Sentry Fits Into the Thunderbolts Movie and Avengers: Doomsday Marvel Cinematic Universe: Every Upcoming Movie and TV ShowWho Is Lewis Pullmans Thunderbolts Character The Sentry?The Sentry is quite possibly the most powerful superhero in the Marvel Universe. Hes also the most dangerous.Once an ordinary man named Bob Reynolds, he consumed a serum that granted him the power of a million exploding suns. Unfortunately, that power comes at an incredible cost. Theres a dark side to The Sentrys personality known as The Void. For every act of good The Sentry performs, The Void counteracts it with an evil deed. Fighting against his inner darkness and maintaining his sanity is a losing battle for Bob Reynolds. Still, when the times call for a powerful hero, theres no one better suited to the job than The Sentry. The Sentry is quite possibly the most powerful superhero in the Marvel Universe. Hes also the most dangerous.The Sentrys Powers and AbilitiesThe Sentrys powers stem from an experimental serum, one of the many formulas developed as a potential replacement for the Super Soldier Serum after World War II. The serum is said to accelerate his molecules an instant forward in time. What that means in practice is that The Sentry is an incredibly strong hero with an almost limitless array of powers.Lewis Pullman as Bob Reynolds, aka The SentryAs The Sentry, Bobs strength is easily on par with heroes like Hulk and Thor. He can also fly and move at incredible speeds, has enhanced senses and is practically invulnerable. He can also absorb and project energy, allowing him to perform feats like firing energy blasts, teleportation and pacifying a rampaging Hulk. In terms of powers, The Sentry is truly Marvels answer to Superman.As The Void, Bob is arguably even more powerful and dangerous. The Void is a shape-shifting, demonic entity that can do everything from controlling the weather to infesting the minds of others. The Void has easily withstood the combined might of the Avengers, X-Men and Fantastic Four, and even throwing it into the sun has proven to be a temporary solution.The Sentry Cheat SheetFirst Appearance: The Sentry #1 (2000)Creators: Paul Jenkins, Rick Veitch, & Jae LeeAliases: The Void, Golden Man, The Golden Guardian of GoodCurrent Team: None (formerly New Avengers, Mighty Avengers, Dark Avengers)Recommended Reading: The Sentry Vol. 1, Age of the Sentry, Dark Avengers, SiegeThe Sentrys Secret OriginThe Sentry was created by Paul Jenkins, Rick Veitch and Jae Lee and debuted in the pages of the original The Sentry miniseries in 2000. That series introduces its title character as a forgotten hero from the Marvel Universes past. Even Bob Reynolds - a middle-aged, overweight married man - doesnt remember that he used to be the hero nicknamed The Golden Guardian of Good.Bob regains his memories and becomes The Sentry once more, only to discover his sworn enemy, The Void, has also returned. Over the course of the series, The Sentrys history with characters like Hulk and the Fantastic Four is established, and The Sentry is retroactively inserted into Marvel continuity.Ultimately, readers learn that The Sentry and The Void are two halves of the same coin. The world was made to forget about The Sentry in order to protect it from The Voids wrath. Bob realizes he has no choice but to repeat that act in order to keep his dark side at bay. He once again erases the worlds collective memory of The Sentry, though the series is ambiguous as to whether Bob himself has truly forgotten about his superhuman selves. Art by Bryan Hitch. (Image Credit: Marvel)The Sentry as an AvengerThe original The Sentry miniseries was a self-contained story, but the character did eventually go on to play a recurring role in the Marvel Universe. The Sentry officially became one of Earths Mightiest Heroes in 2004s New Avengers, joining a radically revamped team alongside characters like Spider-Man, Wolverine and Luke Cage. New Avengers reintroduces The Sentry as a self-imposed prisoner of The Raft, one who intervenes to stop a massive supervillain jailbreak and reluctantly joins the team in the aftermath. Though a powerful asset to Earths Mightiest Heroes, The Sentry fights to preserve his sanity and once again keep The Void at bay.When the worlds heroes are torn apart by the events of 2006s Civil War, The Sentry sides with Iron Mans pro-registration faction. He knows all too well the damage that unchecked power can wreak. The Sentry also proves vital in protecting the world from Hulks wrath in 2007s World War Hulk.However, The Sentrys downfall begins in Marves 2009 storyline Dark Reign. As Norman Osborn takes control of S.H.I.E.L.D.s replacement H.A.M.M.E.R., he recruits Bob Reynolds to join his Dark Avengers. The Sentry is manipulated into serving alongside villains like Bullseye, Venom and Ares. Osborn gambles that all those years of grappling with his Green Goblin persona will allow him to keep The Sentry under control. That turns out to not be the case.The Void art by Olivier Coipel. (Image Credit: Marvel)The Void is finally unleashed in 2010s Siege, which sees Osborn lead an all-out attack against Asgard. The recently returned Steve Rogers rallies the true Avengers and saves the day, though at the cost of The Sentrys life.In the years since, The Sentry has been resurrected and killed again, while new stories have continued to explore the true nature of his powers and the question of whether The Sentry or The Void is the real being. The Sentry was killed once more in 2020s King in Black. Marvels 2023 The Sentry series explores what happens when the power of The Sentry seeks a new host. Who will become the new Sentry, and will they also have to shoulder the burden that is The Void? Only time will tell. How The Sentry Fits Into the Thunderbolts Movie and Avengers: DoomsdayTo date, The Sentry hasnt enjoyed much exposure outside of Marvels comics, apart from appearing in a handful of mobile games like Marvel Puzzle Quest, Marvel Future Fight and Marvel Snap. But that will change soon, as Lewis Pullman has been cast as the Golden Guardian of Good in the MCU.The Walking Dead's Steven Yeun was originally cast as Sentry but the role became vacant after Yeun had to drop out of the Thunderbolts line-up due to scheduling conflicts because the movie got pushed from the 2024 release slate following a major reshuffle in the aftermath of the dual writers and actor strikes, leaving Deadpool & Wolverine as the only MCU movie out in 2024.Pullman wont be starring in a dedicated Sentry movie or series, though (at least, not yet). Instead, hes debuting in 2025s Thunderbolts*, appearing alongside familiar MCU faces like Sebastian Stans Bucky Barnes, Florence Pughs Yelena Belova and David Harbours Red Guardian.Given the characters comic book history, its probably safe to assume the film will play up his status as both a powerful hero and a terrifying villain. Will The Sentry start out as a member of the Thunderbolts, only to become the teams worst nightmare when he loses control? Given the relative lack of powers on this roster, battling The Sentry would certainly be a monumental task for the Thunderbolts.The Thunderbolts: The Tumultuous History of Marvel's Twisted Super-TeamWe may see Julia Louis-Dreyfus Contessa Valentina Allegra de Fontaine play a role similar to that of Norman Osborn in the Dark Avengers comics. Contessa may see Bob Reynolds as a powerful asset to be exploited, only for her control over this dangerously unstable hero to evaporate. If Thunderbolts is basically Marvels version of Suicide Squad, then The Sentry may be the films Enchantress character.We also dont know whether the MCU will touch on the idea that The Sentry is a forgotten hero with deep ties to the rest of the superhero community. Will he be retroactively established as a character who was once very active in the MCU? And just how much will the movie lean on the idea of The Sentry as a twisted analogue of DCs Superman? Well learn more as we move closer to the May 2025 release date of Thunderbolts.As for Avengers: Doomsday, it's now known that Pullman will also be appearing alongside a ton of other actors from across the MCU, not to mention some fellow Thunderbolts players like Florence Pugh (Yelena Belova), David Harbour (Red Guardian), Wyatt Russell (John Walker / U.S. Agent), and Hannah John-Kamen (Ghost). That means Doomsday is going to have characters from Thunderbolts, Fantastic Four, the traditional Avengers line-up from the Infinity Saga, and many more. If The Sentry does become his dark persona in the Thunderbolts film, should we assume that he will overcome that side of him and return to being a force for good before confronting the threat of Robert Downey, Jr.'s Doomsday? Time will tell!Note: this article was originally published on November 17, 2023 and updated on March 26, 2025 with the latest information about Thunderbolts. Jesse is a mild-mannered staff writer for IGN. Allow him to lend a machete to your intellectual thicket byfollowing @jschedeen on BlueSky.