As Carnage makes his big screen debut, one of his co-creators admitted that not only did they not think he'd become so popular, but that they weren't a big fan of Venom to begin with. Following Cletus Kasady's role as the antagonist in Venom: Let There be Carnage, legendary Spider-Man artist Mark Bagley talked with SYFY Wire about creating the character with writer David Michelinie and how their work together was not only popular but continues to inspire both Venom and his murderous offspring decades later.
When David Michelinie introduced Venom with artist Todd McFarlane in Amazing Spider-Man #299, Spider-Man's rejected alien costume became a vengeful alien behemoth with all of Spider-Man's powers who constantly threatened Peter Parker and his life. Although Spider-Man was able to defeat Venom, his host Eddie Brock would constantly find a way to be reunited with the symbiote and continue their enmity until it was rendered comatose by a superhuman virus. When it recovered, it sought out Eddie who was incarcerated in Ryker's Island, sharing a cell with psychotic serial killer Cletus Kasady. After witnessing Venom reunited and its dramatic escape in Amazing Spider-Man #345, Cletus learned the symbiote had secretly left behind an offspring, which bonded with the sadist. Reintroducing himself in Amazing Spider-Man #361 as Carnage, the symbiotic serial killer's powers made him an even greater threat than Venom, requiring Spider-Man to often seek assistance from Eddie more than once in order to defeat the creature.
As Carnage would become a threat not only to Spider-Man but other Marvel heroes as well, he remained a fan favorite villain who would eventually make his way to television, video games and recently movies. In an interview with SYFY Wire from 2018 - which has since been removed from the site - Bagley admitted that he didn't expect Carnage to become so popular. "I had no idea, to be honest. I wasn't a big Venom fan and at the time, I just thought it was another story. I really didn't gather the fact that Carnage was going to be such a big deal."
Carnage was created during the height of Venom's popularity when Marvel decided to not kill Eddie Brock in favor of other hosts taking control of Venom, something ironically that would take place years later. Carnage is a supposed to be a darker version of Venom with the insane Cletus Kasady gleefully using his new powers to rack up an even higher body count, having powers that even Venom didn't possess. Becoming a fan favorite as well, Carnage would headline his own storyline in 1993's Maximum Carnage, make his television debut in Spider-Man: The Animated Series, and continue to be one of Marvel's most unpredictable and dangerous threats regardless of whichever host was in control. Another interesting point is that Bagley would collaborate with Michelinie on Venom: The Lethal Protector, which would become one of the inspirations for 2018's Venom. He continued to return to both characters later in his career on titles like Ultimate Spider-Man or Venom.
Mark Bagley's artwork for both Carnage and Venom is considered one of the most popular by fans, some of this thanks to Marvel using it often for licensed material ranging from cups to shirts to video game promos. New characters are constantly being created in comic book mythology and it's hard to pinpoint when a character will become fan favorite or not. Considering both Carnage and Venom's continued popularity, one can assume Mark Bagley is pleased that he was proven wrong about it being just another Spider-Man story.