David Martijn Westerholt is a Dutch musician and the founder, keyboardist and main songwriter of the symphonic metal band Delain. He was previously a member of symphonic metal band Within Temptation, until he was diagnosed with infectious mononucleosis shortly after the release of Within Temptation's second studio album, Mother Earth. His brother Robert is the guitarist and founder of Within Temptation. He has lived in Zwolle, since studying Communication at Windesheim College in 1998.