What is Reddit's opinion of Spider-Man: Birth of Venom?
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By popularity on Reddit, this product is:

#118 in Superhero Comics & Graphic Novels

#57 in Marvel Comics & Graphic Novels

#693 in Science Fiction & Fantasy books

6 reviews of this product found across Reddit:

I wish I was better with specific arcs but I'm pretty casual in my knowledge. This was the best I could do with the help of google, wiki and amazon, but someone with more knowledge may be able to correct me on some things.

I'd start here:

https://www.amazon.com/Spider-Man-Birth-Venom-Jim-Shooter/dp/0785124985/

It looks like it covers not only the "Alien Costume Saga" which is also available as 2 books on Amazon, but the beginning of the Todd McFarlane Venom story. You may want to check into getting that one though, it seems like maybe some of the alien costume story isn't fully included. This is from the top review: "Prospective buyers be aware, though, that this compilation does not include all of the full issues listed in the Amazon description (also listed on the back cover of the book) -- some of the issues only have a page or two that dealt with the Alien Costume or Venom."

This is Maximum Carnage:

https://www.amazon.com/Spider-Man-Maximum-Carnage-Tom-Defalco/dp/0785109870

They have other Carnage/Venom collections you'll see come up in the recommendations. I've enjoyed other stories but these are the only ones I'm even sure I've read entirely, it was a long time ago. They are mostly origin type stories.

I'll add this to my list, "Spider-Man: Kraven's Last Hunt", which was dark and awesome and very stand alone.

https://www.amazon.com/Spider-Man-Kravens-J-M-DeMatteis/dp/0785134506

Kraven’s Last Hunt. Also there’s a graphic novel on Amazon called Spider-Man: Birth of Venom. It covers alllllll the black suit stuff

Black suit was my favorite too since I was a kid :)

Spider-Man: Birth of Venom https://www.amazon.com/dp/0785124985/ref=cm_sw_r_cp_api_TAz9BbV7G6DSD

Amazing Spider-Man Epic Collection: Kraven's Last Hunt (Epic Collection: The Amazing Spider-Man) https://www.amazon.com/dp/1302907050/ref=cm_sw_r_cp_api_hCz9BbSX0FZ64

His first and repeated appearances as a Spidey villain are great (showing up mostly in Amazing Spider-Man vol. 1 or different trades--1, 2, 3 if that's how you read), but I suppose not really necessary for understanding the movie...Lethal protector would probably be the next thing to scope.

Are you asking for reading recommendations? For now I’ll just give you a rundown.

During Secret Wars, Peter’s suit gets damaged and he finds some machine and thinks it’ll repair his suit, it goes all over him and he’s amazed and continued to wear it, eventually on Earth he realizes it’s alive and gets rid of it, the symbiote now hates Spider-Man and happens to bond wit Eddy Brock, who hated Peter for debunking his fake pictures, Eddy learns who Peter is and targets him.

Carnage is Cletus Cassady, a serial killer who was Eddy’s cellmate. When the symbiote comes to the cell to break Eddy out, it produces a spawn, and that spawn goes onto Cletus and Spidey and Venom (who isn’t purely evil and actually tries to be a good guy) team up to take him down.

Spider-Man: Birth of Venom

Spider-Man: Maximum Carnage

The symbiotes have had a number of hosts over the years. It’s back to Eddy in Venom by Donny Cates Vol. 1: Rex, but before that, it was with Flash Thompson in Agent Venom

People seem to like these. Carnage: Minimum Carnage. The guy on the cover is Kaine, The Scarlet Spider. He’s one of the clones from the 90’s clone saga. Carnage, U.S.A.. Deadpool vs. Carnage.

Spider-Man: Birth of Venom - Collects the first few stories with the black costume and Venom.

If you want to read Venom as a hero then try Venom by Rick Remender: The Complete Collection Volume 1 and Volume 2

Where are you seeing mixed reviews? Amazon and Goodreads are pretty positive.

Some of those Spider-Man issues are from the 1980s which still had a specific writing/art style that may be an acquired taste for some. You'll have to define "comprehensive" in this context. It definitely shows you how Peter Parker brings back a symbiote with him in Secret War (II), fighting crime in the black spider suit, gets help from the Fantastic Four about his suit, in comes Eddie Brock, etc. It's all the early days of Venom. Eventually, there will be other hosts and other characterizations.

This is what I'd recommend for Venom: