Watch : Angelina Jolie, Brad Pitt’s Son Knox Graduates High School Before Competing in Muay Thai FightKnox Jolie-Pitt was red-y for a change. Case in point: Angelina Jolie and Brad Pitt’s youngest son stepped out recently with yet another bold new hairstyle: a grown out, long spikey red dyed ‘do. The 18-year-old debuted the look while on a run in Los Angeles Aug. 10, pairing the new style with a simple cream T-shirt and running shorts. Knox’s latest transformation comes just months after he celebrated his high school graduation—where he referred to himself as Knox Jolie in a ceremony program—by competing in a Muay Thai fight. “I'm gonna knock ‘em the f--k out!”