Playing Ripley in the Alien movies has made Sigourney Weaver one of cinema's most recognisable faces.

As she returns to the big screen in new film Chappie, she tells Susan Griffin about taking risks and reprising her most famous role...

She's had a long and varied career, but there's no question which role she's best known for.

Sigourney Weaver's portrayal of Ellen Ripley, a brave, ballsy astronaut who does her damnedest to save the world from a seriously evil monster in the 1979 film Alien, established her as a force to be reckoned with. Alien, directed by Ridley Scott, blew the male-dominated sci-fi genre apart and paved the way for a new generation of actors.

Now 65, Weaver is going to reprise the role for a fifth time, with Neill Blomkamp (director of District 9 and Elysium) at the helm.

"I think it's very exciting but it's a little difficult for me to believe quite yet," says the statuesque actress, looking elegantly laid-back in dark trousers and blue shirt.

She's full of praise for the 35-year-old South African director, describing him as her first choice to be in control of the film.

"Neill's one of those masterminds. He's comfortable with all of the technology, not only classic science fiction technology, but what's really happening. He's also dazzling visually."

But audiences don't have to wait for the fifth Alien movie to see Weaver back on the big screen.

Her latest film, Chappie, also directed by Blomkamp, sees her play weapons corporation CEO Michelle Bradley.

Chappie is set in the near future, where crime is controlled by a robotic police force who can't be reasoned or negotiated with. When a police droid - later nicknamed Chappie - is stolen and given new programming, he becomes the first robot think and feel for himself.

The film asks what it means to be human through the eyes of Vincent Moore (Hugh Jackman), who sees a thinking robot as the end of mankind, and Chappie's creator, Deon Wilson (Dev Patel), who sees his creation as the last hope for humanity.

She may seem light years from Ellen Ripley, but Weaver says her character in Chappie is groundbreaking too.

"It was fun to play a woman CEO because there are so few of us. I think there were some men considered but Neill ended up making it Michelle and I loved that he did that."

For Michelle, the bottom line is about making money - she doesn't care whether technology is hurting or helping crime levels.

"I think I'd be a different kind of CEO, because if someone said, 'I can make a robot who can think and feel', I'd go, 'Wow, who knows where that can take us'. I think there's more money in creating something new than grinding out what you've already done, but that's why I'm not a CEO," Weaver laughs.

She says she's excited by the concept of artificial intelligence.

"I think it's going to be wonderful. Of course, it all depends on who programmes it. If it's someone like Dev's character, then I think you're going to have a lovely life."

Weaver's had something of a lovely life herself. Born and educated in New York City, Weaver graduated from Stanford University and went onto receive a Master's degree from the Yale School of Drama.

Her first professional job was an understudy in Sir John Gielgud's production of The Constant Wife, starring Ingrid Bergman, before making her film debut in Alien.

Three years later she starred in the first of the Ghostbusters franchise opposite Bill Murray and Dan Aykroyd (she's involved in the upcoming remake starring an all-female cast) and in 1987, received her first Academy Award nomination for Aliens.

Another two years earned a further two nods for her roles in Gorillas In The Mist, where she portrayed primatologist Dian Fossey and Working Girl, in which she played the boss of a secretary out on revenge.

She's since starred in the likes of thriller Copycat, comedy Jeffrey Rush, Roman Polanski's adaptation of Death And The Maiden, and the animated WALL.E. More recently, she's just finished working with The Theory Of Everything's Felicity Jones on "a wonderful movie" called A Monster Calls.

"I think it's important never to repeat yourself, and that's why I've jumped from drama to comedy to sci-fi," she says.

"I'm happy and very comfortable taking risks in my work. You've got to change it up and everyday go, 'I don't know whether I can do this' and that's why it's interesting."

Off-screen, she's married to stage director Jim Simpson, with whom she has a daughter.

"Marriage is the most exciting thing you can do and I've been married for 30 years," she says.

"I married someone I hardly knew, but he's from Hawaii so he had lots of aloha!"

Weaver is currently preparing for the new Avatar films, which will reunite her with Aliens director James Cameron. Her character was mortally wounded in the 2009 Avatar movie, but "no one ever dies in science fiction".

"I just know I'm playing a really cool character so I'm kind of working on it to the extent of what I know," she says.

The three movies, due for release in 2017, 2018 and 2019, will be filmed simultaneously.

"We haven't started yet, but when we do, we'll all probably disappear off the face of the earth for a year-and-a-half."

Chappie is released on Friday, March 6