English merchant, financier, and founder of the Royal Exchange.

Gresham was educated at the University of Cambridge and later trained as a lawyer. He was an agent of the English government in the Low Countries, where he engaged in espionage, smuggled war materials and bullion, and negotiated with his government's foreign creditors. The repayment of loans and interest owed by England caused exchange fluctuations between countries which increased the sums that the English government had to repay; Gresham operated in the foreign-exchange market to alleviate these fluctuations. He understood the power of governments to affect the rate of exchange and even suggested the creation of an exchange-equalization account. It was Gresham who advised Queen Elizabeth I to recoin the currency following her father's debasement of it with inferior metal. Thus, his name would later be associated with the monetary principle, hence known as Gresham's law (q.v.), which may be summarized by the aphorism that “bad money drives out good.”

In order to provide a convenient meeting place for the bankers (exchange dealers) in London, Gresham built the Royal Exchange (1566–68), which at first was called the “Bourse” and received its present name by royal proclamation in 1571.