Donald James Mackay, 1st Baron Reay, 11th Lord Reay,, in the Netherlands known as Donald Jacob, Baron Mackay, Lord of Ophemert and Zennewijnen, was a Dutch–British administrator and Liberal politician.
- Occupation
- politician, aristocrat
- Position held
- member of the House of Representatives of the Netherlands, Member of the Privy Council of the United Kingdom, member of the House of Lords, President of the Institut de Droit International
- Citizenship
- Kingdom of the Netherlands, United Kingdom of Great Britain and Ireland
- Born
- December 22, 1839