The singing icon and actress is set to join Oscar-winner Joaquin Phoenix in the sequel to “Joker,” and the first images of Gaga have been unveiled. US Weekly shared photos of Lady Gaga as Harley Quinn, complete with red blazer, checkered blouse and “signature geometric eyeshadow.” Details are being kept under wraps, but the title of the upcoming sequel has been confirmed as “Joker: Folie á Deux.”