Frits Ferdinand Rudolf Heide (7 December 1883 – 1957) was a Danish botanist and science writer.
He studied botany at the University of Copenhagen from 1906 under professor Eugenius Warming, but never actually graduated.
In 1909, Frits Heide revised J.P. Jacobsen’s translation of Charles Darwin's On the Origin of Species and The Descent of Man.
Much later, in 1935, he finally published his own translation of the Origin of Species.
Heide was a prolific writer in Danish popular science, but also contributed with more purely scientific texts on plant biology, forest history, ethnobotany etc.