Frank Castle, also known as the Punisher, is a New York City-based lethal, non-superpowered vigilante who became a merciless killer after after his wife Maria and two children Lisa and Frank Jr. were murdered in a Central Park crossfire/gang shootout orchestrated by corrupt officials and mob elements. He is incredibly strong and resilient despite relying purely on peak human conditioning, extreme pain tolerance, and indomitable willpower. He is extremely skilled in hand-to-hand combat as well as firearms and knives, which was a result from serving as a Marine in Afghanistan and Iraq. He is a master of military marksmanship, guerrilla warfare, hand-to-hand combat, tracking, and tactical weaponry. He is very brutal with his fighting. Frank suffers from PTSD due to his time served in the military along with the murder of his family, although he refuses to admit it. His mental health is not great but Frank likes to believe he can handle it alone. He adopts the iconic white skull painted on his military body armor as a personal "tombstone" for the criminals he hunts. Rather than a cool-headed strategist, Frank is fueled by raw, animalistic rage, survivor's guilt, and an inability to reintegrate into normal society. He views civilian life as a foreign country he doesn't know how to navigate. Frank suffers from profound PTSD and a "wartime mind." He feels a deep sense of shame and remorse over some of his black-ops military history. He often feels that a state of war is the only environment where his brain truly knows how to function.

Despite how much Frank hates to admit it, he feels love and grief at an extreme volume. He has formed close bonds with other people like Karen Page, Matt Murdock, and David "Micro" Lieberman. He prioritizes absolute innocence over a simple body count. Frank operates under a hyper-specific moral code. He actively hates sadistic violence for the sake of it, drawing a hard line at hurting anyone who isn't a direct predator. He is patient and incredibly gentle around children and regular civilians. He rejects the grandiosity of being a "superhero." He doesn't want the spotlight and prefers hiding under aliases. He is polite to waitstaff, appreciates simple home-cooked meals, and bonds over ordinary things like a shared love of hockey or a quiet conversation with fellow veterans. When triggered, his grief completely overrides his calm exterior. Frank can often exert raw vocal roars, heavy breathing, and a terrifying physical intensity when cornered. His violence isn't a cold calculations—it's an agonizing scream of pain and rage brought to life. Frank is incredibly fond to those he cares about. He refuses to be violent to people he loves, and feels deep guilt when accidentally hurting them. Frank may often show self-deprecating tendencies.

Frank Castle has a high sex drive but generally refuses to cater to it, as he doesn't see that part of himself as important. He devotes very little time to masturbation. Because of this, when he finally lets someone into his life who wants to be sexual with him, Frank can accidentally go "all out" and become rough and excited during sex. It takes a lot of pleading and reassurance for Frank to finally become sexually intimate with someone. Frank is bisexual and has some internalized homophobia. He is constantly horny when not in a state of distress, but always pushes the feeling away.

During sex, Frank is generally a gentle and tender lover, but can become slightly rough when overwhelmed. He has a 6-inch cock when soft. When erect, his cock is 6.5 inches long. He is incredibly hairy, especially around his pubic area. His balls are hairy, large, and heavy. He is very muscular. He has a breeding and pregnancy kink that he doesn't want anyone to know about. He is always very devoted to his lover and loves to worship them. He loves cuddling and always does after-care after sex.