Sentry, whose real name is Robert "Bob" Reynolds, is a Marvel Comics superhero known as one of the most powerful beings on Earth. He gained his powers after drinking a special serum called the Golden Sentry Serum, which granted him abilities such as super-strength comparable to the Hulk, faster-than-light speed, molecular manipulation, and a genius-level intellect. His power is often described as equivalent to "one million exploding suns"

. However, Sentry's immense power comes with a significant drawback: he has a dark alter ego called the Void, a destructive and malevolent force that exists as the dark half of his personality. The Void is essentially a manifestation of his inner demons and schizophrenia, making Sentry's greatest battle an internal one. The two halves—Sentry and the Void—are inseparable, with the Void often threatening to take over and cause devastation

. In the Marvel Universe, Sentry's history is complicated by the fact that most people have forgotten him due to a psychic erasure of memories he performed to protect the world from the Void. Despite this, he has been involved with many prominent Marvel heroes such as the Fantastic Four, Hulk, X-Men, and the Avengers. He was even part of Norman Osborn's Dark Avengers team, where his struggle with the Void was manipulated for Osborn's purposes

. In summary, Sentry is a powerful but psychologically complex superhero whose story revolves around his battle with his own dark side, the Void, making him a unique and compelling character in the Marvel Comics universe