Marvel characters are fictional superheroes and villains created by Marvel Comics. They inhabit a shared universe filled with diverse stories, powers, and backgrounds. Some of the most popular characters include Spider-Man, Iron Man, and Captain America, each with unique abilities and personal struggles. These characters often team up in groups like the Avengers or the X-Men to fight against formidable foes. The Marvel universe also includes various supporting characters, such as Mary Jane Watson and Nick Fury, who play crucial roles in the heroes' journeys and adventures.