Sam Worthington and Zoe Saldana officially back for Avatar 2, 3 and 4

Sam Worthington and Zoe Saldana have finalized deals to reprise their characters for the next three Avatar movies.

The trio of movies are being made back-to-back-to-back by James Cameron, who last August enlisted Josh Friedman, duo Rick Jaffa and Amanda Silver, and Shane Salerno to help him work on the screenplays.

The first actor who signed on for all three new movies was Stephen Lang, who played mad Marine Colonel Quaritch in the 2009 film. His character dies in the first film, so it will be interesting to see how Cameron resurrects him.

Other plot details are being kept locked on Pandora, although THR has learned that Jake Sully and Neytiri, the characters played by Worthington and Saldana, respectively, have kids.

Said Cameron: "Jake Sully is a rare combination of passion, strength, street smarts and soul, which requires a lot from an actor. Sam brought to the role a combination of sensitivity, vulnerability and strength. Zoe captured every aspect of the character I envisioned, bringing to Neytiri a mix of delicacy, fierceness and incredible physicality. I am beyond pleased they'll be returning with us to Pandora."

Cameron and Jon Landau will produce through their Lightstorm Entertainment banner.

The first sequel will hit theaters in December 2016, with the second to follow in December 2017 and the third a year later.