Robert Westerholt (born 2 January 1975) is a Dutch musician, known as the guitarist and co-founder of the symphonic metal band Within Temptation.

In 1992, Westerholt formed the band "The Circle" with future Within Temptation keyboard player Martijn Spierenburg,[1] and he began writing his own music.

[1] In a 1995 compilation album released by DSFA Records, two songs, "Broken Silence" and "Frozen" by The Circle, were featured.

In 1998, he had a small singing part as Death (along with George Oosthoek of Orphanage) on the Ayreon rock opera "Into the Electric Castle", on which Sharon den Adel played one of the main characters.

Westerholt and Sharon den Adel became parents to Eva Luna on 7 December 2005 and Robin Aiden on 1 June 2009.