BURBANK, CALIF. — A number of key stars of “Avengers: Age of Ultron” — Chris Hemsworth, Chris Evans, Scarlett Johansson, Mark Ruffalo, James Spader and Paul Bettany — shared one common thought as we chatted about the film near the soundstages on the set of Walt Disney Pictures: A love of the witty zingers writer/director Joss Whedon had packed into the script.

Spader and Bettany — who portray two new characters in the “Avengers” film franchise: Ultron and Vision — both noted that it was the writing of this second “Avengers” movie that drew them into the world of comic book motion pictures.

Bettany said that the “ad lib” feeling of much of the dialogue — as the various characters kidded each other and poked fun at individual foibles — was due to “Joss being a very, very witty man. For James and I and the scenes we had together, I felt they were packed with a lot of wit. I don’t mean gags either,” added Bettany. “I mean pure wit.”

Spader agreed. “That’s the genius of Joss Whedon. He creates spontaneous moments on film. Of course, they aren’t spontaneous at all, but they feel like they are. He allows for something in  his writing that brings in a certain amount of surprise — and then adds dialogue among the characters to add commentary on that surprise.”

For Chris Hemsworth, who plays Thor, the language of the “Avengers” works because it makes the characters “so relatable to the audience. “Each of these characters represent the archetypes of people in the world around us. Here’s my point: If you would pick a classroom in almost every school, you’d find examples of these characters. There’s the nerdy guy. There’s the earnest, well-behaved kid. There’s the smart-ass. There’s the athlete. … In a funny way, we’re all big kids, long after we leave school, and these films represent a blown-out, fantasized version of those schoolrooms we all attended. That’s why all of this is so relatable.”

Picking up on the “relatable” theme, Chris Evans (“Captain America”) added another take on why he believes fans flock to the “Avengers” films, plus the other Marvel movies that showcase the characters seen in “Avengers: Age of Ultron.”

“People love these characters because they are characters they have known for decades. These are not new characters we’re introducing. That’s why these movies are successful. We have a built-in audience. It’s a fan base who have grown up with these characters

“Marvel doing a good job to ensure that those people — those diehard fans who have a very specific vision for each one of these characters — are met properly and satisfied. That’s a job and a responsibility that we as actors share in as well.”

As for director and writer Whedon, these Marvel characters “combine things that have always made comic books work: A combination of the familiar and the idealized.

“‘He’s a god! He’s a billionaire! He’s from the 1940s!’ But along with those fantasy-tinged aspects, they all have very down-to-earth, very human qualities too. While Thor is a god, he doesn’t exactly fit in. He can’t get through doors. He’s got a little bit of awkwardness. All the characters have that sort of feet-of-clay aspect to them.

“That’s a big part of what makes them relatable to us mortal humans.”

Yet, Scarlett Johansson thinks a lot of the responsibility for the audience connecting to the “Avenger” films must be credited to Whedon.

“He really approaches these films as intimate, character-driven stories. The explosive parts and all the amazing special effects, are just the exciting popcorn bits that everybody gets a rush from, and enjoy.

“Sure, he wants everything to look bad-ass, and he definitely knows how to hold a gun! But he makes such an effort to pay attention to each character — to give us these very well-rounded stories that incorporate our origin story, yet also drives the plot forward. We were very lucky to have a director that can helm something this huge and also keep it so intimate.”

Ruffalo (The Incredible Hulk) agreed. “Joss adds a lot of humor to it all as well, but he also adds-in the real-life kind of struggles that people go through. That’s what helps make it so relatable.

“I remember Joss saying, ‘I think all great movies share one thing: They’re about families. Families working out issues.’

Ruffalo started to laugh. “Of course, the cast of ‘Avengers’ is like everyone’s dysfunctional family. When people watch it, they go, ‘Why does this seem so familiar? This is really funny to me, though it shouldn’t be.’

“It’s because it hits way too close to home,” added Ruffalo.