I. Lewis "Scooter" Libby (first name generally given as Irv, Irve or Irving; born August 22, 1950) is an American lawyer and former chief of staff to Vice President Dick Cheney. He became known as a high-ranking staff person to be indicted by a grand jury on charges related to an intelligence investigation. He was convicted but later granted clemency by one Republican president and fully pardoned by Republican president Donald Trump.

From 2001 to 2005, Libby held the offices of Assistant to the Vice President for National Security Affairs, Chief of Staff to the Vice President of the United States, and Assistant to the President during the administration of President George W. Bush.

In October 2005, Libby resigned from all three government positions after he was indicted on five counts by a federal grand jury concerning the investigation of the leak of the covert identity of Central Intelligence Agency officer Valerie Plame Wilson. He was subsequently convicted of four counts (one count of obstruction of justice, two counts of perjury, and one count of making false statements), making him the highest-ranking White House official convicted in a government scandal since John Poindexter, the national security adviser to President Ronald Reagan convicted in 1990 in the Iran–Contra affair.

After Libby's failed appeal and a high-pressure lobbying campaign for Libby's full pardon by Vice President Cheney, President Bush commuted Libby's sentence of 31 months in federal prison, leaving the other parts of his sentence intact. As a consequence of his conviction in United States v. Libby, Libby's license to practice law was suspended in 2007, for a period of at least five years. He gained reinstatement in 2016. President Donald Trump fully pardoned Libby on April 13, 2018.

Libby was born to an affluent Jewish family in New Haven, Connecticut. His father, Irving Lewis Leibovitz, was an investment banker. His father changed his family's original surname from Leibovitz to Libby.

Libby graduated from the Eaglebrook School, in Deerfield, Massachusetts, a junior boarding school, in 1965. The family lived in the Washington, D.C., region; Miami, Florida; and Connecticut prior to Libby's graduation from Phillips Academy, in Andover, Massachusetts, in 1968.

He and his elder brother, Hank, a tax lawyer (now retired) were the first in the family to graduate from college. Libby attended Yale University in New Haven, graduating magna cum laude in 1972. As Yale Daily News reporter Jack Mirkinson observes, "Even though he would eventually become a prominent Republican, Libby's political beginnings would not have pointed in that direction. He served as vice president of the Yale College Democrats and later campaigned for Michael Dukakis when he was running for governor of Massachusetts." According to Mirkinson: "Two particular Yale courses helped guide Libby's future endeavors. One of these was a creative writing course, which started Libby on a 20-year mission to complete a novel ... [later published as] The Apprentice ... [and] a political science class with professor and future Deputy Secretary of Defense Paul Wolfowitz. In an interview with author James Mann, Libby said Wolfowitz was one of his favorite professors, and their professional relationship did not end with the class." Wolfowitz became a significant mentor in his later professional life.

In 1975, as a Harlan Fiske Stone Scholar, Libby received his Juris Doctor (J.D.) degree from Columbia Law School.