Six Marvel Comics superheroes - Iron Man, Captain America, Black Widow, Hawkeye, Thor and Hulk - have joined forces to fight evil in Joss Whedon's Avengers Assemble, which hits cinema screens on Thursday, April 26. The star-studded cast reveal what it's like to be part of the biggest superhero movie ever made.

By Shereen Low.

A bit like buses, you wait years for a superhero to come along then suddenly loads turn up at once.

Later this summer, Spider-Man and Batman will be returning to silver screens, in The Amazing Spider-Man and The Dark Knight Rises respectively. But before that comes Avengers Assemble - a superhero extravaganza, in which no less than six Marvel Comic favourites unite, in the ultimate world-saving dream team.

Robert Downey Jr, Scarlett Johansson, Chris Hemsworth and Chris Evans have reprised their super-skilled alter-egos - Iron Man, Black Widow, Thor and Captain America - while newcomers Mark Ruffalo and Jeremy Renner join the pack as The Incredible Hulk and Hawkeye, for Joss Whedon's highly anticipated blockbuster based on the Marvel Comics series, The Avengers, first published in 1963.

The film's plot sees top secret international intelligence agency S.H.I.E.L.D (Strategic Homeland Intervention Enforcement Logistics Division) tasked with a world-saving mission, as Thor villain Loki, played by Tom Hiddleston, is threatening to destroy earth.

S.H.I.E.L.D leader Nick Fury, brought to life by Samuel L Jackson, calls in the superheroes.

Here's a closer look at the baddie-busting line-up...

Iron Man (Tony Stark) - Robert Downey Jr As the self-described "genius, billionaire playboy philanthropist", armoured superhero Stark is also the go-to guy for the Avengers, after previously agreeing to be a S.H.I.E.L.D consultant in Iron Man 2.

"Joining the Avengers is an act of curiosity - he wants to see what's happening first-hand," Downey Jr explains.

Unlike his alter-ego, who is reluctant to get involved at first, Downey Jr couldn't wait to get stuck in and meet his star-studded team.

"I think more now that I'm 46, I should be in this phase of my development where you appreciate things while they're happening, and this is one of the first times I really had that feeling throughout the production," he says.

"From five years ago, when we did the first Iron Man to today, it couldn't have gone any better. This is the one instance in my life that has gone well and I'm still riding high on it."

Black Widow (Natasha Romanoff) - Scarlett Johansson Johansson loved playing the butt-kicking Romanoff, a valued member of S.H.I.E.L.D given her credentials as one of the world's best spies and skilled assassins.

"It's nice to be able to play a female character that's not a damsel in distress or some woman-in-waiting, but to actually play someone who's got a lot of conviction and who is really ready to kick some booty," she says.

"You always want the opportunity to do different things and not be pigeon-holed so it was very exciting to do something like this - I never thought I would."

The 27-year-old actress had little hesitation about squeezing back into the Black Widow's unforgiving catsuit, despite having to resort to a "green" diet.

"You're training and doing all that stunt work so you eat a lot of green things," she admitted.

Johansson, who did a lot of training for her role, admitted it wasn't always easy doing most of the stunts.

"The whole thing was just one big injury - you get used to it. You just grin and bear it," she added.

The Incredible Hulk (Bruce Banner) - Mark Ruffalo Following Edward Norton and Eric Bana's previous incarnations, the mean, green giant has undergone a transformation with Ruffalo - even in full fierce form, he is physically smaller.

"I liked the idea that I would be the first actor to play both Banner and the Hulk. That was most exciting to me, that we have reached a place with technology where an actor could do that," he says.

The 44-year-old, who was inspired by his young son's rages, jumped at the opportunity to portray a superhero.

"As a kid, I was a Hulk fan, and I was a particular fan of the TV show," he says.

"I loved the idea of being able to bust out the big, green mean machine, even if I was by myself most of the time, which was lonely."

However, Ruffalo admits that filming left him feeling green with costume envy.

"I had to wear a leotard, which reduced me to a Chinese checker board. It made all the wrong places look big and all the right places look small," he jokes.

Thor (God Of Thunder) - Chris Hemsworth Things get personal for Thor in Avengers Assemble, as he joins Fury's unlikely alliance to prevent his wayward brother Loki from destroying the world.

"Joining the team is tricky because he [Thor] has a more personal objective than the rest of them. His brother Loki is the one who's causing the chaos and he fears that the others may just want to kill him, instead of stopping him and taking away his powers," says the Australian actor.

The brothers are forced to face each other in battle on screen, but in real life, the actors are nothing but good mates.

"Some of my favourite stuff [in the film] is with Tom because we've had a relationship on and off screen. Most of my meaty scenes were with him," adds 28-year-old Hemsworth.

Hawkeye (Clint Barton) - Jeremy Renner As one of S.H.I.E.L.D's most elite agents, Barton, code-named Hawkeye, is the greatest living marksman on earth, and in Avengers Assemble is introduced to the big screen for the very first time.

"What I liked more than anything was the idea that he's a human being with a high skill set, who is a bit of a rogue agent," says 41-year-old Renner, who adds that when he was offered the role: "I said, 'As long as I'm not in purple tights, let's do this!'"

He certainly didn't regret the decision.

"I've played a few snipers before and there's a really interesting mentality that comes along with being a sharp shooter, so I thought it was pretty fun to play."

Captain America (Steve Rogers) - Chris Evans At the end of his 2011 movie, Captain America crashed into the Arctic and froze. But now, decades later, he has defrosted - just in time to help save the world.

"Waking up in modern day is just an extremely different way of life that Steve Rogers now has to get used to," says Evans.

"It's not just that Captain America wakes up in a whole new world; it's the fact that he has to deal with the emotions of finding out that everybody he knows is dead."

The 30-year-old admits that the Captain doesn't have it easy when he joins his fellow supers.

"The others give him a bit of grief in this one. He's just trying to do the right thing, but he has some hurdles," Evans adds.

Loki - Tom Hiddleston After his bid to overthrow the throne of Asgard was thwarted by brother Thor, the angry demi-god plots deadly revenge against his sibling and the world.

"I get to be the ultimate baddie in a big blockbuster. Loki is terrifying. That's cool!" says Hiddleston.

The English actor, who learnt various fighting techniques including Wushu, boxing, knife work and hand-to-hand combat for the role, admits that he sometimes wished he'd possessed his alter-ego's godly powers during training, after smashing his elbow on set.

"I have bruises all over my body," he says. "There was a moment when Loki has a throw-down with the Hulk and essentially, I had to jump backwards and land on my back, but I just landed on my elbow!

"There was a real crunching sound on my funny bone, and I thought, 'I've been in a fight with Chris Evans and he hit me and I didn't get injured. Chris Hemsworth has hit me in the face and I hadn't got injured there, but now I've injured myself'. What an idiot basically!"