Wilhelmus Jacobus Duyn (31 March 1937 – 4 December 2004) was a Dutch singer, actor, entertainer and voice over artist.

During the 1960s Duyn was a popular musician; he had performed in many Dutch bands such as Whiskers and the Jay-Jays.

In 1972, "How Do You Do" reached the top of the charts throughout Continental Europe and Scandinavia and peaked at number 32 in Australia, made popular by local bands Jigsaw and Windows.

Following several successful hits the duo represented the Netherlands at the Eurovision Song Contest in Brighton, with I See a Star that finished third on the night.

Duyn died on 4 December 2004 after suffering a cardiac arrest, at his home in Roswinkel, Drenthe, Netherlands.