Sentry

Before any powers, Robert Reynolds was a broken man. He grew up running from a violent father, hiding in his own bedroom, and as an adult he sank into drug addiction. When the chance came to join an experimental program, he signed up. He didn't have much to lose.

The program was the Sentry Project, run by OXE, a company tied to Valentina Allegra de Fontaine. The idea was to repeat, with a variation of the super-soldier serum, what had worked with Steve Rogers. The other volunteers died. Bob was the only one who survived.

With the project about to become a scandal, Valentina sends Yelena Belova, John Walker, Ava Starr and Antonia Dreykov to the same facility, each thinking they have a different mission. In reality, she wants them to kill each other and the place to be incinerated with all the evidence inside. In the middle of the chaos, Bob comes out of a stasis chamber, with no idea who he is.

He helps the group escape, and already shows strange signs. When he touches Yelena and Walker, both are thrown back into their worst memories. Bob also survives things that would kill anyone and flies off out of control. He ends up recaptured and taken to the old Avengers Tower, now renamed the Watchtower.

Valentina sees Bob as the answer to her problems: a superhero all her own, more powerful than any Avenger, ready to be presented to the public. Bob accepts the role and puts on the suit.

When the future Thunderbolts break into the Watchtower, he shows just how big this is. He flies, takes any hit, moves objects with his mind and takes down the whole group almost effortlessly. He spares their lives, but the power goes to his head, and he starts seeing himself as a kind of god.

The experiment created more than a hero. Inside Bob is the Void, a dark figure made of the depression and insecurity he's always carried. When a fail-safe is triggered, the Void takes control and covers New York in darkness. Anyone touched by the shadow disappears and gets trapped in their own traumatic memories.

Yelena walks into that darkness on purpose. She passes through her own memories as a trained killer and finds Bob hiding in a re-creation of his childhood bedroom. The other Thunderbolts arrive next, and the group goes with him through his abusive father, his addiction and the room where the Sentry procedure happened. The Void tries to crush them. What wins isn't strength: it's the group surrounding Bob, hugging him and making it clear he's not alone. With that he takes back control.

Valentina rushes in front of the cameras and introduces the group as the New Avengers, taking credit for the rescue. Bob becomes part of the team. The power is still there, and so is the Void, which makes him both the strongest and the most dangerous member of the team.

Lewis Pullman is confirmed in the cast of Avengers: Doomsday, which opens December 18, 2026. Nothing about the plot has been revealed.

Created by Paul Jenkins and Jae Lee, the Sentry debuted in 2000 with a curious premise: he was supposedly an old Marvel hero that everyone, himself included, had forgotten. In the comics Bob gets his powers from an experimental serum and spends years not understanding that the Void is another side of himself. Later he joins the Avengers and keeps his own Watchtower.