Rien Poortvliet (7 August 1932 – 15 September 1995) was a Dutch artist.
He illustrated the book Gnomes, among others.
- Gnomes (1976)
- The Pop-Up Book of Gnomes (1979)
- Secrets of the Gnomes (1982)
- The Complete Gnomes (1994)
- Gnome Songs (1998)
- Gnome Life (1999)
- A Gnome's Christmas (2004)
After a stint in the Navy, Rien rose to senior manager at Lintas, Unilever's ad agency. On the side, he illustrated various books for several publishers.