Ludwig Wilhelm Carl Rehn (April 13, 1849, Bad Sooden-Allendorf – May 29, 1930) was a German surgeon.
Rehn was born in 1849, in the village of Allendorf, the youngest of five children.
After the visiting the convent school in Bad Hersfeld, he studied medicine at the University of Marburg from 1869 to 1874, where he became a member of the student corps Hasso-Nassovia.