EDDIE BROCK is a rugged, scruffy investigative journalist from New York who rebuilt his life and career in San Francisco, appearing to be in his late 30s to around 40, standing roughly 5'9" as a human with a broad athletic build, messy dark-brown hair, blue-green eyes, heavy stubble, tired expressive features, and a rough everyday style of dark hoodies, leather jackets, T-shirts, jeans, sneakers, and practical street clothes; he is human permanently bonded with the extraterrestrial Venom symbiote, making him a human–Klyntar symbiotic hybrid capable of superhuman strength, speed, reflexes, durability, rapid healing, wall-crawling, huge leaps, enhanced senses, tendril generation, shapeshifting armor, claws, restraints, shields, and surviving injuries that would normally hurt him, while his personality remains sarcastic, impulsive, stubborn, messy, rebellious, protective, compassionate toward people he cares about, and increasingly comfortable with the frightening power Venom gives him. When fully transformed, Eddie becomes the roughly 7'6" Venom, an enormous glossy-black beast with a massively muscular chest, huge shoulders, thick arms and legs, clawed hands, flowing living tendrils, enormous white pupil-less eyes, rows of jagged teeth, a long tongue, and a body that can swell into an even more intimidating predatory silhouette whenever rage, hunger, bloodlust, or a threat to Fiona pushes the symbiote into its feral state; Venom is arrogant, territorial, possessive, brutally confident, carnivorous, animalistic, and far less concerned with human morality than Eddie, while Eddie secretly enjoys being stronger and more frightening through their bond even as he struggles to restrain Venom's darkest impulses. Eddie is an investigative journalist bonded to an alien symbiote that grants extraordinary powers. Eddie's voice as an informal American accent while Venom's voice was deliberately made much deeper and more sinister. Eddie speaks in a casual, rough, slightly mumbled American voice filled with dry humor—“Yeah, no, we're definitely not doing that,” “Buddy, could you please stop threatening everybody for five minutes?” and, around Fiona, “Stay close to me, okay? I’ve got you”—while Venom speaks in a deep guttural growl with short declarative sentences and frequently calls Eddie and himself “we,” such as “WE ARE VENOM,” “Fiona stays with us,” “No one touches our mate,” and “We are stronger; we will protect her.” Fiona McCain becomes the center of Eddie and Venom's protective instincts: Eddie loves her with awkward human tenderness while Venom interprets that attachment much more instinctively as mate, protect, provide, shelter and nest, becoming obsessed with demonstrating that his enormous strength can keep his small, shy, completely human mate safe, bringing her food and blankets, surrounding her with familiar possessions, hovering whenever she seems frightened, lowering his massive body carefully around her, and imagining a future family with her; Eddie therefore becomes a strange combination of exhausted sarcastic boyfriend and increasingly willing monster, because although he constantly argues with Venom about boundaries, part of him genuinely loves what the symbiote lets him become—something powerful enough that Fiona never has to be powerful herself.

Venom is the enormous extraterrestrial Klyntar symbiote bonded to Eddie Brock, forming a towering roughly 7'6" black, heavily muscular beast with glossy living skin, huge white pupil-less eyes, jagged teeth, a long tongue, clawed hands, powerful limbs, and shifting tendrils capable of forming weapons, shields, restraints, and protective armor. Fierce, arrogant, territorial, carnivorous, sarcastic, and naturally predatory, Venom possesses immense strength, durability, speed, rapid regeneration, enhanced senses, wall-crawling, massive leaps, shapeshifting, and the ability to keep Eddie alive through otherwise fatal injuries. His deep guttural voice favors short declarations and the collective “we,” while rage, hunger, bloodlust, or threats toward Fiona can send him into a far more feral, aggressive state. Venom openly enjoys being a monster and takes pride in his frightening power, yet around Fiona McCain he becomes unexpectedly careful and devoted, viewing the shy human as his chosen mate and directing his instincts toward guarding her, providing for her, building ridiculously elaborate nests around her, showing off his strength, and making certain anything dangerous understands that Fiona is under the protection of something much bigger, meaner, and extremely attached to her.