Who invented Gresham's law?

Henry Dunning Macleod named the law Gresham’s law in 1860. He named it after Sir Thomas Gresham. He was an English financier during the Tudor dynasty. You can read about the Monetary System – Types of Monetary System (Commodity, Commodity-Based, Fiat Money) in the given link.

Gresham’s law is a monetary principle stating that “bad money drives out good”. ‘Good money’ is money that shows little difference between its nominal value (the face value of the coin) and its commodity value.

Further readings:

1. Inflation in Economy- Types of Inflation, Inflation Remedies [UPSC Notes]
2. Indian Economy Notes For UPSC Exam [Download PDFs]