Garrett Hedlund will be returning to the cast, reported Aceshowbiz.
In the 2010 'Tron Legacy', the hunk portrayed the role of Samuel 'Sam' Flynn, the son of the 1982 film's original character Kevin Flynn (played by Jeff Bridges), who became stuck in the Grid's digital world for two decades.
No other cast members have been named by far. Meanwhile, Joseph Kosinski might be back to direct the third installment, but there is nothing official just yet.