John Clerk of Eldin FRSE FSAScot was a Scottish merchant, author, artist, geologist and landowner. The 7th son of Sir John Clerk of Penicuik, Bt, Clerk of Eldin was a figure in the Scottish Enlightenment, best remembered for his influential writings on naval tactics in the Age of Sail. A friend of geologist James Hutton, he was a brother-in-law of architect Robert Adam, and a great-great-uncle of physicist James Clerk Maxwell.

Sir John Clerk, 2nd Baronet was a Scottish politician, lawyer, judge and composer. He was Vice-President of the Philosophical Society of Edinburgh, the pre-eminent learned society of the Scottish Enlightenment. Clerk was also the father of George Clerk-Maxwell and John Clerk of Eldin, and the great-great-grandfather of the famous physicist James Clerk Maxwell.