Rehn is a Scandinavian surname, also used in Finland.
- Elisabeth Rehn, Finnish politician, the country's first female Minister of Defence
- Frank Knox Morton Rehn, American artist
- Olli Rehn, Finnish politician, European Commissioner for Economic and Monetary Affairs and the euro
- Stefan Rehn, Swedish football player and manager
- Trista Rehn, Trista Nicole Sutter (née Rehn), the first Bachelorette
- Victor Rehn, physicist, former Director Office of Naval Research, Asia-Pacific.