The Avengers: Age of Ultron is one of the most anticipated movies of the year. Get ready for the blockbuster with these facts about the comic book heroes. Trivia buffs, assemble!

• In 1963, the first issue of Marvel Comics’ Daredevil was delayed going to the printer, forcing the company to scramble to release something. Top artist and creator Stan Lee suggested an easy way to put a comic together was teaming up a bunch of existing characters together, imitating rival DC Comics’ Justice League.

• For the sake of time and not confusing non-comics fans, the Avengers movies feature only a handful of members of the superhero team. Since introduced in 1963, the Avengers have had a rotating lineup of dozens of characters. The initial members were Iron Man, Thor, and Hulk (as depicted in the films), with the addition of Ant-Man and Wasp. Later additions included such obscure characters as Moondragon, Hellcat, Falcon, Quasar, Stingray…and Forgotten One.

• In the U.K., The Avengers is a popular spy TV show from the 1960s (it had a cult following in the U.S.) that’s more well known than the comic book. When Marvel’s The Avengers was released in Great Britain in 2012 it was done so under the name Avengers Assemble.

• Amanda Peet nearly got the role of Agent Hill (it went to Cobie Smulders) and Emily Blunt turned down the role of Black Widow, which went to Scarlett Johansson.

• Mark Ruffalo did motion capture work for his CGI-oriented role as the Hulk…whose body was modeled after a stripper named Steve Romm.

• Gwyneth Paltrow plays Tony Stark/Iron Man’s assistant, Pepper Potts, and she almost always appears barefoot. Reason: Producers wanted Robert Downey Jr. (Iron Man) to appear taller than her, an effect achieved by making Paltrow barefoot and putting Downey in platform shoes.