The fan-made names for the Life Foundation symbiotes - Agony, Lasher, Phage, and Riot - were canonized in the Carnage USA arc.
The name "Agent Venom" was used by fans to refer to Flash Thompson's black-ops Venom form, and was quickly canonized once Flash joined the Secret Avengers.
Creator's Favorite: Cullen Bunn mentioned that he constantly tries to include Mania in every story he's hired to write but kept getting turned down for various reasons. As such, he was just as shocked and upset as her fans were when Dan Slott and Mike Costa stripped her of her symbiote in Venom Inc., though he rolled with it and started coming up for new adventures for her sans-symbiote. Following the conclusion Absolute Carnage: Scream, he lamented on Twitter that he wasn't likely to be given an opportunity to write her or any symbiotes again.
David Michelinie had intended right from the start to kill Eddie Brock off once Venom had become popular, and have the symbiote jump from host to host. Marvel kiboshed that in light of the character's popularity as an antihero, so he came up with Carnage as a replacement. In 2004, Mark Miller penned a story where Eddie and the symbiote went their separate ways, and while he is currently Venom, it's had four main hosts and counting.
Cullen Bunn had intended to resurrect Anti-Venom for the third volume of the Venom series, but those plans were kiboshed by Marvel cancelling it after Volume 2 was finished. In AXIS: Hobgoblin, a new Anti-Venom cameos as one of Hobgoblin's enfranchised superheroes, though it's not explained who's wearing it or how Kingsley got his hands on a specimen of the supposedly-deceased symbiote. In Venom Inc. Flash Thompson is exposed to an astrobiological serum derived from the original Anti-Venom while fighting with Eddie Brock over the symbiote, and is transformed into Agent Anti-Venom as a result.
An early idea for Venom was to have the symbiote bond to a woman who lost her child due to a car accident caused by a motorist being distracted by a fight involving Spider-Man. This discarded concept was seemingly recycled into the minor villain Coldheart, whose son was implied to have been a casualty of a battle possibly involving Spider-Man.
One of Mark Bagley's early "Chaos" (Carnage) designs◊ was more or less reused for Scream.
The symbiote was originally going to have a female host, but this was reportedly rejected by Jim Salicrup (editor at the time).
It's very obvious that Mike Costa's run was cut short to make way for Donny Cates' run; the result was Costa's run not having a proper ending by the time Cates' run started. Costa was later given the Venom: First Host miniseries to wrap up his story.
Broxin for Eddie Brock as Toxin. Fans have also started to call Eddie's look in Carnage Vol. 2 "Agent Toxin" due to its resemblance to Flash's appearance as Agent Venom.
In a more derisive example, "Sasuke" for Lee Price from Mike Costa's run largely because of his design and the large amounts of Character Shilling for someone the fans despise.
Carnage-Man for the inverted Carnage during his AXIS miniseries.
The Merch: The Xenophage got an action figure, though the packaging referred to him as "Phage◊".
Official Fan-Submitted Content: The design for Spider-Man's black suit was created by a fan named Randy Schueller, who submitted it to a contest. Mike Zeke altered it slightly by changing the chest and hand emblems from red to white, and the symbiote was born.
Saved by the Fans: David Michelinie's original intent was to kill Eddie off and have the symbiote jump from host to host, but Marvel vetoed the plan due to the character's runaway popularity.
Screwed by the Network: Someone at Marvel's editorial department seems to have had a grudge against Andi Benton — despite her being a fan favorite — and Cullen Bunn in general, seeing how all of his requests to include her in stories (aside from Venomverse) were vetoed, he was left in the dark about Dan Slott and Mike Costa being given the go-ahead to depower her in Venom Inc., and when asked why he didn't re-empower her in Venomized he replied that he'd been worried he'd be told to kill her off. This culminated in Bunn severing his working relationship with Marvel in 2019, following his writership of Absolute Carnage: Scream. It's implied that being passed over for writing Scream: Curse of Carnage may have been the straw that broke the camel's back.
David Michelinie's original concept for Venom was a young woman who went insane after she miscarried due to witnessing her husband get run over by a taxi driver accidentally distracted by Spider-Man — which is why the hand that shoves Spider-Man in front of a train is that of a woman. However, the editor-in-chief at the time — Jim Salicrup — rejected the idea due to thinking a woman wouldn't be threatening enough to make for a serious supervillain. After this pitch was rejected, Eddie Brock was subsequently created and the Sin-Eater storyline was used for his origin.
David Michelinie stated in an interview that he'd planned for Eddie Brock to be killed off early on and the symbiote to jump from host to host. Marvel refused to let him kill the character in light of his popularity as an antihero, and Carnage was created instead. Flash forward ten-odd years and, while Eddie isn't dead,note Though he had almost been killed off after Angelo Fortunato's death.the Venom symbiote's had several subsequent hosts.
When Cullen Bunn was devising his half of Venom Vol. 2, he had an idea for the Venom symbiote to spawn a demonic version of itself possessing the Hell Mark, which would bond to Eddie Brock. However, he decided that Eddie and Toxin needed more time together, and developed his Devil Venom idea into Mania.
Rick Remender and Cullen Bunn had a number of story arcs planned out for the third volume of the Venom series, including tying up the Descent subplot; the return of Anti-Venom for a "War of the Symbiotes" arc also featuring Mania and Toxin;note In April 2020 Remender released an overview of the event, which would have involved the symbiote homeworld being destroyed by Symbiote Hunters, the Toxin symbiote going into heat and releasing countless spores that would result in a worldwide symbiote plague, Spider-Man learning Flash Thompson was Agent Venom, Carnage taking over the symbiote-infected New York City, and Eddie Brock sacrificing himself to stop Toxin. Crime Master coming back from the dead. Marvel's cancellation of the series flushed those plans down the dumper. Also, Eddie Brock was supposed to become Demon Venom/Mania, but wound up becoming Toxin while new character Andrea Benton became Mania. That said, a new Anti-Venom cameos as one of Hobgoblin's underlings in AXIS: Hobgoblin, Flash Thompson becomes Agent Anti-Venom in Venom Inc., and Venom: Space Knight touches on the Descent subplot with Mania.
The Venom: Carnage film that was to be a spinoff from the The Amazing Spider-Man Series was cancelled in 2015, following a deal between Marvel and Sony.
Carnage was originally going to be called Ravage, until it was found out that DC Comics had recently come out with a character of that name.