Judd Alan Gregg (born February 14, 1947) is an American politician and attorney who served as the 76th governor of New Hampshire from 1989 to 1993 and a United States senator from New Hampshire from 1993 to 2011 where he was Chairman of the Health Committee and the Budget Committee. A member of the Republican Party, he was a businessman and attorney in Nashua before entering politics. Gregg currently serves as the Chair of the Public Advisory Board at the New Hampshire Institute of Politics at Saint Anselm College.

Gregg was nominated for Secretary of Commerce in the Cabinet by President Barack Obama, but withdrew his name on February 12, 2009. He chose not to run for reelection to the Senate in 2010; former State Attorney General Kelly Ayotte, also a Republican, was elected to succeed him.

On May 27, 2011, Goldman Sachs announced that Gregg had been named an international advisor to the firm. In May 2013, Gregg was named the CEO of the Securities Industry and Financial Markets Association, a Wall Street lobbying group. He later stepped down as CEO in December 2013 and became a senior adviser.

For the 2016 presidential election Gregg endorsed former Florida Governor Jeb Bush, and upon Bush's suspension of his campaign Gregg endorsed Ohio Governor John Kasich. In the 2024 Republican Party presidential primary, he endorsed Nikki Haley.