John Gallagher, Jr. is known for originating the role of Moritz Stiefel in Duncan Sheik and Steven Sater's rock musical Spring Awakening, which earned him a Tony Award for Best Featured Actor in a Musical.
He also played Johnny in Green Day's Broadway musical, American Idiot, and Lee in the 2011 Broadway production of Jerusalem.
Until 2014, he played Jim Harper in Aaron Sorkin's The Newsroom.
In 2015, he was featured in the television movie Olive Kitteridge.