Samuel Augustus Nunn, Jr. (born September 8, 1938) is an American lawyer and politician. Currently the co-chairman and Chief Executive Officer of the Nuclear Threat Initiative (NTI), a charitable organization working to reduce the global threats from nuclear, biological and chemical weapons, Nunn served for 24 years as a United States Senator from Georgia (1972 until 1997) as a member of the Democratic Party. His political experience and credentials on national defense reportedly put him into consideration as a potential running mate for Democratic candidate John Kerry in the 2004 Presidential election. There was speculation that he could have been the running mate of Democratic candidate Barack Obama in 2008. Nunn is an informal advisor to President Obama.

Nunn was born in Macon, Georgia and raised in nearby Perry, and he grew up with family connection to politics; he was a grandnephew of the Congressman Carl Vinson.

Nunn is an Eagle Scout and recipient of the Distinguished Eagle Scout Award from the Boy Scouts of America. In high school, Nunn was a standout athlete, captaining the school's basketball team to a state championship.