Harwell may refer to:

• Harwell - a village in Oxfordshire
• RAF Harwell - a World War II RAF airfield
• Harwell Laboratory of the Atomic Energy Research Establishment, the site of Europe's first nuclear reactor.

Other organisations on the old Harwell airfield site are also loosely referred to as "Harwell", such as Harwell International Business Centre and Rutherford Appleton Laboratory.