Kate Winslet has joined the cast of the 'Avatar' sequels.

Kate Winslet

Kate Winslet

The 41-year-old British actress first collaborated with director James Cameron on the 1997 multi-Oscar winning disaster movie 'Titanic', and now Winslet is reuniting with Cameron to be part of his sci-fi universe, which is getting four sequels to the 2009 original.

Winslet will play a character called Ronal, but it isn't yet clear whether her alter ego will be a Na'vi or a human.

Cameron told Variety: "Kate and I have been looking for something to do together for 20 years, since our collaboration on 'Titanic', which was one of the most rewarding of my career. I can't wait to see her bring the character of Ronal to life."

Winslet will be working alongside a host of returning cast members, such as Zoe Saldana, 38, Sam Worthington, 40, and Sigourney Weaver, 67.

Cliff Curtis will also star in the movie as Tonowari, the leader of the Metkayina, the reef people clan, in the Cameron-directed movies - all of which are poised to take place under water.

Cameron recently revealed, the first movie will be released in 2020, followed by the other three in 20121, 2024 and 2025.

He wrote: "Great to be working with the best team in the business! Avatar takes flight as we begin concurrent production on four sequels. The journey continues December 18, 2020, December 17, 2021, December 20, 2024 and December 19, 2025!"

Cameron also defended the 11 year gap since the first movie claiming the delay was due to creating the "overall vision."

He said in May: "It was a seven year gap between 'The Terminator' and 'Terminator 2: Judgment Day', seven year gap between 'Alien' and 'Aliens'. It's going to be obviously more like a ten year gap between 'Avatar' and 'Avatar 2'. But 'Avatar 2' you are going to with not the promise but the certainty of three more films beyond that, and that's a very different concept with the audience. And a lot of the delay has been around creating that overall vision."

The first 'Avatar' film, released in 2009, still remains the highest grossing movie at the worldwide box office, raking in as much as $2.79 billion.