From Bulbapedia, the community-driven Pokémon encyclopedia.
David Kos "Music Man" Rolfe is an artist who has written and performed songs for the English dub of the Pokémon anime. He has a record label from Warner/Chappel Production Music and continues to make music as of 2017.
Working under the 4Kids dub, he performed five English theme songs, namely Born to Be a Winner, Believe in Me, I Wanna Be a Hero, This Dream, and Unbeatable. He currently lives in New York City.