Pieter Collier is a widely recognized collector of over a thousand works of Tolkien literature. He founded and maintains TolkienLibrary.com, and is a Library Consultant and webmaster for the Greisinger Museum, a private Swiss museum of Middle-earth-inspired art and paraphernalia. He is a strong promoter of the art of Tolkien illustrator Cor Blok.
The North East Tolkien Society, a former division of the Tolkien Society in New York, presented Collier with their "Imperishable Flame Award" in 2006 and 2007 for his contributions to Tolkienian fandom.
In 2011, Collier contributed the article "Collecting Tolkien Books, from Hobbits to Dragons — There and Back again" to the Lembas journal of the Dutch Tolkien Society. In the same year he compiled A Tolkien Tapestry: Pictures to accompany The Lord of the Rings, a portfolio of some of Cor Blok's art, published by HarperCollins.
He resides in Antwerp, Belgium.