Peter Hollens is an American pop singer and producer best known for his work on YouTube as an a cappella cover artist. With over 950,000 subscribers, his videos have reached more than 100 million viewers since 2011. Hollens has collaborated with some amazing artists, including Jason Mraz, Hunter Hayes, Lindsey Stirling, George Watsky & Tyler Ward. He has released over 85 digital singles and has been involved with a cappella music since 1999 when he co-founded the University of Oregon’s male a cappella group On The Rocks. In 2010, he was featured on NBC’s The Sing Off Season 2 with On the Rocks.