Judith Carol Lewent is a business executive who served as chief financial officer of Merck & Co. from 1990 until her retirement from the company in 2007.

in 1972 from the MIT Sloan School of Management with thesis titled The French Open-end Investment Companies (1964 to 1971): an Application of the Capital Asset Pricing Model.

In 1990, on her appointment as CFO, Lewent took on responsibilities for Merck's overall financial and strategic development, and for licensing matters.

Since then Lewent has also been responsible for Merck's collaboration with Johnson & Johnson in a consumer pharmaceuticals joint venture, for the setting up of the animal health company Merial (a joint venture with the French pharmaceutical company Sanofi-Aventis), and for Merck's ongoing relationships with AstraZeneca and DuPont.

Between 26 July and 07 Aug 2007, Lewent sold 200,000 shares of Merck stock for about $10,262,000, according to Securities and Exchange Commission filings.