Made this list for fun and if your aware of tvtropes and Villains wiki then you know what a big bad is the primary antagonist of the story ,series,or franchise. Also to note not all of the villains count as big bads if they are just recurring villains or one-offs,Bigger Bads,arc villains,and archenemy isn't always the big bad. So anyway is a list of most well known big bads in the Marvel Universe.
- Norman Osborn/Green Goblin and Doctor Octopus from Spider-man
- Thanos from Guardians of the Galaxy.
- Magneto and Apocalypse from X-men
- Ultron and Kang from Avengers
- Red Skull and Baron Zemo from Captain America
- Mandarin from Iron Man
- Jigsaw from Punisher
- Kingpin from Daredevil
- The Leader from Hulk
- Loki and Malekith from Thor
- Supreme Intelligence from Captain Marvel
- Dormammu from Doctor Strange
- Doctor Doom From Fantastic Four
- Mephisto from Ghost Rider and Sliver Surfer
- Erik Kilmonger and Klaw from Black Panther.
- Selene in the original New Mutants and Necrosha arc.
Well since that is all I can find which big bad did you think I miss and which is your favorite?