Ryan Jerome McCartan (born June 14, 1993) is an American actor and singer. As an actor, he is known for playing Jason "J.D." Dean in the original off-Broadway production of Heathers: The Musical (2014) and for playing Brad Majors in the 2016 Fox musical television film The Rocky Horror Picture Show: Let's Do the Time Warp Again. McCartan is also known as half of the former pop duo The Girl and the Dreamcatcher. McCartan played the recurring role of Diggie Smalls on the Disney Channel sitcom Liv and Maddie. He also played Fiyero, the main love interest, in the Broadway production of Wicked. He was also the final Hans in the Broadway production of Frozen.