Baron Guy François Edouard Marie Ullens de Schooten Whettnall (born 31 January 1935) is a Belgian art collector, philanthropist, and former businessperson.
Following his business career, he has with his wife, Myriam Ullens, established the Guy & Myriam Ullens Foundation, known for the Ullens Center for Contemporary Art in Beijing, China, and for founding the Ullens School in Lalitpur, Nepal.