From Bulbapedia, the community-driven Pokémon encyclopedia.
John Loeffler (sometimes credited as John Leffler or Joe Loeffler) is a producer, writer, and singer for the English dub of the Pokémon anime.
As CEO of Rave Music, he has been in charge of all the music for the U.S. localization of the show since its inception. Loeffler has produced all of the original music for the series, including album releases, movie scores, dub scores, and the Pokémon Live! show. He has written, composed, or arranged a majority of the tracks with many composers including John Siegler (also of Rave), David Wolfert, and Norman J. Grossfeld, producer of the 4Kids dub. He was involved in producing the opening themes from seasons 1-4, and has written and produced the English opening themes from the ninth season to the sixteenth season of the anime. John is also respectably credited for composing and writing the lyrics of the seventeenth season opening theme as the song was based on the first season's opening theme.
He has provided lead vocals for:
Profile and Interview with John Loeffler, 2000