As you may or may not know, the studios aren't able to freely use characters as they please because certain studios own the rights to specific characters. Despite the fact that in the comic books The Avengers collaborate and appear next to Spider-Man and the X-Men, including them in the same movie is... well, it's complicated.
Hugh Jackman, who is probably most famous for his role as Wolverine,
Hugh Jackman, who is probably most famous for his role as Wolverine,