Vex is the main antagonist of Sackboy: A Big Adventure. He's an almost mythical entity born of chaos and fear.
This most deadly diabolical device will transform Craftworld from a fantastical land of pure imagination and innocent dreams… into a torrid, barren eyesore of nightmares. Ooh the fiend!
Vex seems to be a red and navy blue jester with glowing eyes, a stitched-mouth, three wires for arms, three sharp fingers, navy blue gloves, a ripped up cape, and black boots.
Vex's name means to make (someone) feel annoyed, frustrated, or worried, especially with trivial matters, this seems to match his behavior in the game. (From Google)