Rudolf Karl Theodor Drost (19 August 1892, Oldenburg - 3 December 1971, Wilhelmshaven) was a German ornithologist best known for his studies on bird migration conducted at the Heligoland observatory.
He received a Doctoral degree in 1923 for studying crustaceans and was appointed in the Prussian Biological Station on Heligoland where he continued the work of Hugo Weigold.
He organized student observers along the coast and his capture and ringing of birds also led to improved identification and sexing techniques.
One of his studies included keeping birds in Faraday cages to find that the migratory onset was not influenced by changes in the Earth's magnetic field.
He championed bird conservation and created large-scale ringing networks and helped found the magazine Vogelzug.