Ryan Jerome McCartan (born June 14, 1993) is an American actor and singer. As an actor, he is known for his recurring role as Diggie Smalls on the Disney Channel sitcom Liv and Maddie, and for his role as 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 one half of the pop duo The Girl and the Dreamcatcher. McCartan also played Jason "J.D." Dean in the Los Angeles (2013) and the original off-Broadway (2014) versions of Heathers: The Musical. He also played Fiyero, the main love interest, in the Broadway production of Wicked. He is currently portraying Hans in the Broadway production of Frozen.
McCartan began his career with a minor part in the stage version of Disney's High School Musical in 2007. In 2011 he starred in the titular role in Minnesota's first regional production of The Phantom of The Opera that same year, he won Best Performance by an Actor at the Jimmy Awards, given out by The Broadway League to the top performers in high school musical productions.