Claude Roy Kirk Jr. (January 7, 1926 – September 28, 2011) was an American businessman, politician, and Marine Corps veteran who served as the 36th governor of Florida from 1967 to 1971. A member of the Republican Party for most his career, he was the first Republican governor of Florida since Reconstruction.

In 1943, Kirk enlisted in the United States Marine Corps, serving in the American theater during World War II. After graduating with a bachelor's degree from Duke University and a Juris Doctor from the University of Alabama, Kirk was recalled to the Marine Corps to serve in the Korean War. In 1956, Kirk established a life insurance company in Jacksonville. In 1964, he was the Republican nominee for U.S. senator, losing to incumbent Democratic senator Spessard Holland.

In 1966, Kirk was elected governor, defeating Democratic nominee and Miami mayor Robert King High. His tenure occurred during a tumultuous time in American history, serving during the Vietnam War, the civil rights movement, desegregation, massive population growth in Florida, and the Apollo 11 launch from Merritt Island. His governorship coincided with the 1967 Tampa riots, the ratification of 1968 Florida Constitution, the court-ordered remapping of state legislative districts, the downfall of the Pork Chop Gang, a statewide teachers' strike, and the re-creation of the office of Lieutenant Governor of Florida. After narrowly winning the Republican primary, Kirk was defeated for re-election by state senator Reubin Askew in 1970.

Returning to the Democratic Party, Kirk ran for governor in 1978, for president in 1984, and for U.S. senator in 1988. Kirk rejoined the Republican Party in 1990, and was nominated for Florida education commissioner that same year, losing to incumbent Democrat Betty Castor. On September 28, 2011, Kirk died in his sleep, at the age of 85, at his home in West Palm Beach.

Kirk was born in San Bernardino, California. Claude R. Kirk Jr.'s father, Claude Kirk Sr. was a businessperson and later a governmental official in Alabama and Florida. He lived in Chicago, Illinois, and Montgomery, Alabama, where he attended Sidney Lanier High School. After graduating at age seventeen, he enlisted in the U.S. Marine Corps reserve and rose to the rank of second lieutenant, having served stateside during World War II. He briefly attended Emory University in Atlanta, Georgia, before he transferred to Duke University in Durham, North Carolina, where he earned a Bachelor of Science degree. Kirk was accepted at the University of Alabama School of Law in Tuscaloosa and graduated in 1949. He was recalled to the Marines for the Korean War and was initially assigned to the 1st Marine Division. He later served aboard the battleship USS New Jersey and was discharged as a first lieutenant in 1952.

Kirk worked as an insurance salesman and sold building supplies before partnering with W. Ashley Verlander in 1956 to start the American Heritage Life Insurance Company in Jacksonville, Florida. He had very little money of his own, so he recruited investors and his brother-in-law to bankroll the venture. The firm catered to the wealthy and quickly became one of the most successful in the industry, earning Kirk a fortune. Six years later, he left American Heritage Life and purchased a partnership in the New York securities firm, Hayden Stone, selling investments to Floridians.

In 1960, Kirk switched his party affiliation from Democrat to Republican and headed the "Floridians for Nixon" campaign, which helped the Republican Party win the state's then ten electoral votes for the third consecutive time.

In 1964, Kirk ran as a Republican against veteran Democratic US Senator Spessard Holland, a former governor and epitome of the Florida Democratic establishment. He was considered a placeholder on the ballot, with Republican presidential nominee Barry M. Goldwater losing Florida to U.S. President Lyndon B. Johnson. Kirk polled 36.1 percent of the vote.