If you thought the Russos pulled off a masterstroke in balancing Ciivl War's many characters and sub-plots, you're going to be amazed when they try an even bigger trick with Avengers: Infinity War. Already billed as the comic book movie event to end them all (or at least to kick off a new phase), the film is clearly big in terms of story, but it's also incredibly large in cast terms too.
Previous estimates put the number of characters at 67, but there's been some to and fro since then on who will appear and it's only been fairly recently that characters as big as the likes of Spider-Man have been confirmed. But who else has definitely made the cut?
There are some wildcards of course - Quicksilver's name has been mentioned in rumours for a while now, despite him being dead, for instance and The Wasp is apparently not going to be involved (since she hasn't even put on the suit yet). And then there are supporting characters (like Nova Prime, Odin, General Ross and the Warriors Three) who at this stage probably won't be confirmed until they're in the film. Mostly because they aren't that important.
Bigger question marks hang over those characters who will appear in Phase 3 before the big gig but who might not actually make it out alive: Heimdall has a big question mark hanging over him, and so too does Loki (as unthinkable as it is that Marvel would kill the latter off). Confirming them now would rob Marvel of the revelation that they live, so you'll have to wait.