René Daniel Haller (born 18 December 1933 in Lenzburg, Switzerland), is a Swiss naturalist trained in horticulture, landscaping and tropical agronomy.
Since the 1970s, he has been known for his commitment to environmental restoration, such as the restoration of a limestone quarry wasteland in Mombasa, Kenya, into the nature park and wildlife sanctuary named Haller Park.
He was one of the first recipients of the prestigious Global 500 Roll of Honor by the United Nations for his 'outstanding environmental achievements.
In 1987, Haller was awarded the prestigious UNEP Global 500 Roll of Honor by the United Nations, for his 'outstanding environmental achievements'.
In 1991 he received the Swiss Brandenberger prize, as well as an Honorary Doctor's degree from the University of Basle.