It's almost comical how many big baddies that Spider-Man has taken down over the decades.
Despite initially being created as a means of completely grounding the idea of the superhero into then modern reality and seeing what would happen, the web-head has gone toe to toe with enemies that, quite frankly, should regard him the same way an elephant would regard an ant with a bad limp.
However, for every cartoonishly powerful villain that this teenager who can stick to walls has taken down, there are just as many who have given Parker a nice dosage of reality. Today we'll be giving those villains the spotlight.
The main rule is simple: Spidey HAS to have fought and been unable to defeat them alone. Villains he's never even fought at all is a completely different - and likely very boring - list entirely. (Spider-Man never went head to head with the Man-Elephant - tragic, I agree.)
If he had legitimate outside help that he would not have won the fight without, then it counts for this list.
At the bottom of this list is, naturally, its least surprising entry. Shock of all shocks, the mad titan has never felt threatened by the kid from Queens in a red and blue body stocking.
Which is not to say that Thanos and Spidey haven't fought multiple times. it's just that every time they have, Peter has been at best an afterthought while Thanos takes on the bigger heroes that have come with Spider-Man.
The most famous time that these two have come to blows has, of course, been the original Infinity Gauntlet event comic, where Thanos attained the Infinity Gauntlet and gems to ascend to a higher plane of existence, and all to get Death-senpai to notice him. Spider-Man is among the many heroes recruited by Adam Warlock to act as meat shield distractions for Thanos so that Adam can find a way to get the gauntlet off of him.
Yeah, as you can probably surmise, Spidey does not last long. Thanos isn't even the one who kills him, instead outsourcing that to his artificial henchwoman Terraxia.