Avatar producer Jon Landau has confirmed that Oona Chaplin will play the leader of the Fire Na'Vi in the third movie, and that there will be a big time jump between it and Avatar 4 and 5.
Speaking with Empire, Landau again confirmed that Avatar 3 would introduce us to a more antagonistic people within the Na'Vi, known as the Ash People. Game of Thrones star Oona Chaplin is set to star as their leader, though we've not had much other information confirmed about her character as yet.
We've known Chaplin, who is the granddaughter of Charlie Chaplin, was set to be in the third movie for some time, but this is the first confirmation of her being the leader of the Ash People. Speaking on how they will be portrayed in the movie, Landau said "there are good humans and there are bad humans. It's the same thing on the Na'vi side. Oftentimes, people don't see themselves as bad. What is the root cause of how they evolve into what we perceive as bad? Maybe there are other factors there that we aren't aware of."
The producer also confirmed Avatar 3 and the fourth and fifth movies would be separated by a time jump. He then revealed that the 5th movie will visit Earth, and show us what the dying home world of the humans looks like.