Given just how many people were on screen at the end of Avengers: Endgame, you might think everyone is an Avenger. That's been pretty much the case in the comic books as well, especially as the comics haven't excluded any characters whose rights may be held by competing movie studios.
Finding someone who wasn't affiliated with the team was harder than winning the letter, but believe it or not, there are fairly notable heroes from across the Marvel Universe who have never assembled for the Avengers. Let's take a look at ten heroes who would still have to do rookie chores at Avengers Mansion if they got the call.
10 Scarlet Spider
He may be a clone, but the Scarlet Spider is still a hero. And he was never part of the Avengers. Ben Reilly grew out of the infamous Clone Saga and was the only Friendly Neighborhood Spider-Man for a time. Once all that clone confusion about Peter Parker was cleared up (was it though?) Ben became the Scarlet Spider and struck out on his own. He stayed pretty confined to the Spidey corner of the Marvel Universe, doing the right thing, dying, coming back, the usual.
9 Colleen Wing
A descendant of samurai warriors and 100% bad-ass K'un L'un martial artist, Colleen Wing has everything it takes to be an Avenger, but so far hasn't been. Associate of Misty Knight, Iron Fist and Luke Cage, Colleen is typically identified with more street-level threats like The Hand or Kingpin but that hasn't stopped people like Daredevil or the aforementioned Iron Fist from joining up. With some much-needed recognition in the Marvel Netflix series, maybe she'll get her due.
8 Misty Knight
Speaking of, fellow Daughter of the Dragon Misty Knight was also never an Avenger. At least in the main continuity. She was part of the Luke Cage led Avengers in the alternate timeline of House of M. Another benefactor of the Marvel Netflix experiment, Misty has been around long enough and packs a big enough punch that she would make a great Avenger. With a bionic arm made out of vibranium - and diamond! - and a skill set that makes her an incredible fighter, detective and leader, she should be part of the team.
7 Cyclops
A lot of X-Men have been Avengers. A lot. You'd think Scott Summers would have been at some point, considering how long he's been around and how powerful he is with those optic blasts.
Perhaps owing to the fact he retired from being a superhero after the death of Jean Grey, Cyclops has stayed pretty involved on the X side of things (it's enough really when you think about it). Plus, there was that whole Avengers Vs. X-Men thing where he kind of, you know, murdered people.
6 Polaris
A longtime member and associate of the X-Men, Polaris has never been an Avenger. This despite some pretty heavy connections to the team. Lorna Dane is a powerful mutant who controls magnetism, just like her father Magneto. Probably goes without saying that his daughter Scarlet Witch is a noted Avenger. Lorna's one-time fiancee, the mutant Havok, was a member of the Uncanny Avengers. All this, coupled with her considerable power-set, should have made her a candidate, but so far, she hasn't gotten the call.
5 Silver Sable
A mercenary and owner and operator of a private merc firm, Silver Sable is probably not a natural candidate to be an Avenger. Still, Silver Sablinova has fought on the side of good more often than not. She's also been a regular ally of many Avengers over the years including Spider-Man and Daredevil. She has no superpowers, but she's a highly skilled and trained martial artist. And she carries around a lot of weapons. Just a lot. In a post-Snap world, she'd be a go-to Avenger no questions asked.
4 Colossus
One of the heaviest hitters in the entire Marvel universe, Colossus has never been an Avenger. Though he's punched a few. Actually, he might have punched most of them. Able to cover his body in steel and punch through just about anything, he would be on any shortlist to join the team. Given that other popular X-Men like Wolverine and Beast have joined the Avengers from time to time, it only makes sense that Pitor Rasputin would do the same given the opportunity.
3 Silver Surfer
One of the most powerful cosmic heroes with a tendency to cross paths with the Avengers, Silver Surfer is a curious omission. It might just be his solitary nature. The former herald of Galactus mostly just wants to live a normal life, or as normal as he can get.
Normal isn't really something you can expect with the Avengers. Also, when he shows up, it's not always a good sign. But you do want him on your side though and he would be a tremendous asset for the team. Thought maybe not right now.
2 Rom The Space Knight
He was a toy, but never an Avenger. Despite his deep connections to several Marvel characters - including one Avengers related one in Rogue - Rom the Space Knight never was part of the team. A cyborg, a cosmic superhero, a silvery cool-looking dude, Rom battled villains called the Dire Wraiths and did so once alongside the Avengers. The toy bombed back in the 80s but Rom lasted quite a while in the comics. Some would love to see him in the movies, but not all.
1 Jean Grey
An Omega-level mutant who simply cannot stay dead, she'd be a no-brainer for any team, especially one that runs into as many galactic headaches as the Avengers. Still, Jean Grey has never been part of the team. True enough, she has enough drama with the X-Men. If the Avengers ever did need a hand, they wouldn't have to look past her for any more help. Jean can do things with her mind that would render most, if not all, of the Avengers primary competition moot.