For all of the incredible adventures that are seen onscreen, there are far more that will probably never be known in their entirety.
Child of the Storm
- Apparently, Thor and the National Grid do not mix.
- That time when Wanda told the Order of the Phoenix who her father was, Sirius refused to believe her in extremely tactless fashion and promptly got laid out by Lily. According to Sirius, she [Lily] had a vicious right hook.
- There was, apparently, an incident involving Clint Barton, Hal Jordan, Agent Sitwell and a bungee cord.
- During Jane's building of her Earth based Bifrost, she accidentally warped Darcy into another dimension where she 'did shots with a hot goth girl called Didi'.
- This seems to have been a frequent problem, with Darcy having apparently also ended up in what she claims was the Cretaceous. Jane counters that it was the Upper Jurassic. According to Darcy, this doesn't matter because whatever the case, there were dinosaurs all over the place.
- And then, shortly after this revelation, she ends up as a test dummy for a similar device and being warped to New Jersey. Apparently, she preferred the Jurassic.
- On a darker note, it's never directly specified what Sean Cassidy did to the IRA cell that murdered his wife with his Compelling Voice, but it was bad enough that even now, it sometimes gives Nick Fury nightmares.
- Wanda once offered one of the Little Folk a cup of coffee. The results were ugly enough to make her swear not to do it again.
- Coulson heavily implies that he was betrayed by a wizard he thought he knew and could trust, but is sparing with the details. He also has bad memories of dealing with Death Eaters.
- Alan Scott worked with and alongside Coulson, Fury, and Xavier occasionally.
- How, exactly, did Regulus Black survive the Inferi who killed him in canon and go from renegade Death Eater to protege of Nick Fury and member of MI13?
- Wisdom mentions that Constantine owes him a favor, which he used to get Constantine onto the Excalibur team.
- Mentioning Fenrir Greyback to Wolverine is enough to make the latter furious, though it's unclear if they've met or if Logan just knows him by reputation.
- Wanda Maximoff has met Ebenezar McCoy before, and respects him enough that she states it's an honor to be compared to him.
- John Constantine mentions having had some dealings with Margaret Dresden.
- When Harry got christened, James, Sirius, John Constantine and Nick Fury went through six bottles of Firewhiskey and took Sirius' motorbike, a barrel of grease and a herd of enchanted badgers to a Quidditch match.
- Strange has trained in K'un L'un, enough to master the Iron Fist. A passing comment by Shou-Lao in the third book reaffirms that he knows, or at the very least, knows of Strange.
- While Magneto and Alan Scott clashed multiple times, there was at least once that they worked together.
Ghosts of the Past
- No one's entirely sure of the full details of what happened with Jack O'Neill and a pre-Deadpool Wade Wilson in East Germany back in 1988, but it involved a bunch of Stasi Agents, the Hellfire Club (and possibly its leather drag), a swimming pool full of black market Ben & Jerry's ice cream, and O'Neill and Wade doing an Abba cover. Oh, and O'Neill got a 'trick knee' out of it and swore to shoot Wade into space if he ever saw him again. Whatever else happened there, O'Neill casually remarks that it's weirder than being chased by conjured nightmare Chitauri and TIE Fighters while piloting a conjured version of the Millennium Falcon.
- While he was the Winter Soldier, Bucky encountered Mar-Vell and Sabretooth at different times. Bucky noted that Mar-Vell seemed like a decent man.
- Just before Harry and Maddie's battle in the Nevernever, Wanda and Dresden were busy fighting tentacle demons in Japan, tentacle demons apparently summoned by a coven of magically inclined Otaku with the wrong magic book, with Dresden making 'unspeakable jokes about sushi and Japanese pornography.' Wanda also got a whole lot of impervious to magic gunk all over her and in her hair.
- Bucky implies that the question of whether using dismembered undead giants as projectiles counts as "living weapons" or "unliving weapons" has actually come up before.
- Strange, later, implies that he has had to explain to someone why their dog dissolved (apparently, it's very awkward), and also had someone forget who he was until he committed genocide, having done so multiple times.
- In the course of his life, he also met Orpheus, whom he regards as a bad listener, and Jason Blood, whom he refers to as an old friend.
- Apparently, he's been worshipped as a god at least once, and had to take steps to discourage it.
- He also has had multiple apprenticeships in Atlantis, and at least two (probably more) degrees in psychology.
- Dracula loathes Doctor Strange and his word games, though whether they've encountered each other in person or Dracula just knows his reputation is unclear (the narration implies the former).
- Luccio mentions that she's seen Magneto fight prior to Bloody Hell. Whether this was against Alan Scott or someone—or something—else is unclear.
- Magneto himself implies that Bloody Hell is not the first time he's crossed swords with Selene. At the very least, he states that he knows very well how dangerous she is.
- It's heavily implied that Donald Morgan has gone up against Voldemort before. At the least, Morgan is very familiar with the Avada Kedavra, enough to identify it immediately by the side effects.
- Deadpool once pulled a contract for IKEA (an intellectual property dispute got messy), earning a free lifetime supply of Swedish meatballs and a testimonial on his website.
- He also got too close to some explosives in Jacksonville while trying to get a look at Alison's derriere, and as a result of that (or possibly something else from the same mission), owes her a significant favor.
- Gorakhnath is familiar with Dumbledore, Joshua, and Thanos, having corresponded with the former.
- Frigga hints that the Norns used to manipulate history as Doctor Strange did, and it's further implied that he... took issue with this.
- While at school, Lily and the Marauders met Eldest Gruff in the Forbidden Forest. He took a liking to her.
- Michael Carpenter notes that he has met Wanda Maximoff at least once before she started dating Harry. As with the Ebenezar example, given their jobs, it's very likely this doubles as an Offscreen Moment of Awesome.
- Jor-El visited Earth several times, once being falsely accused of murder and cleared by Hiram Kent, and earlier helping Peggy and a team of allies rescue Alison from the Red Room. He also seems to have been friendly with Loki.
- Prior to the food fight in the Great Hall, Seamus Finnegan had had to regrow his eyebrows sixteen times. In less than two months.''
