John Sidney McCain III (August 29, 1936 – August 25, 2018) was an American statesman and naval officer who represented Arizona in the United States Congress for over 35 years, first as a U.S. representative from 1983 to 1987, then as a U.S. senator from 1987 until his death in 2018. A member of the Republican Party, he was the party's nominee in the 2008 presidential election.

Born into the prominent McCain family in the Panama Canal Zone, McCain graduated from the U.S. Naval Academy in 1958 and received a commission in the U.S. Navy. He became a naval aviator and flew ground-attack aircraft from aircraft carriers. During the Vietnam War, he almost died in the 1967 USS Forrestal fire. While on a bombing mission during Operation Rolling Thunder over Hanoi in October 1967, McCain was shot down, seriously injured, and captured by the North Vietnamese. He was a prisoner of war until 1973. McCain experienced episodes of torture and refused an out-of-sequence early release. He sustained wounds that left him with lifelong physical disabilities. McCain retired from the Navy as a captain in 1981 and moved to Arizona.

In 1982, McCain was elected to the House of Representatives, where he served two terms. Four years later, he was elected to the Senate, where he served six terms. While generally adhering to conservative principles, McCain also gained a reputation as a "maverick" for his willingness to break from his party on certain issues, including LGBT rights, gun regulations, and campaign finance reform where his stances were more moderate than those of the party's base. McCain was investigated and largely exonerated in a political influence scandal of the 1980s as one of the Keating Five. He then made regulating the financing of political campaigns one of his signature concerns, which eventually resulted in the passage of the McCain–Feingold Act in 2002. With Russ Feingold, McCain would receive the 1999 John F. Kennedy Profile in Courage Award. He was also known for his work in the 1990s to restore diplomatic relations with Vietnam. McCain chaired the Senate Commerce Committee from 1997 to 2001 and 2003 to 2005, where he opposed pork barrel spending and earmarks. He belonged to the bipartisan "Gang of 14", which played a key role in alleviating a crisis over judicial nominations.

McCain entered the race for the 2000 Republican presidential nomination, but lost a heated primary season contest to George W. Bush. He secured the 2008 Republican presidential nomination, beating fellow candidates Mitt Romney and Mike Huckabee, though he lost the general election to Barack Obama. McCain subsequently adopted more orthodox conservative stances and attitudes and largely opposed actions of the Obama administration, especially with regard to foreign policy matters. In 2015, he became Chairman of the Senate Armed Services Committee. He refused to support Donald Trump in the 2016 presidential election and later became a vocal critic of the first Trump administration. While McCain opposed the Obama-era Affordable Care Act (ACA), he cast the deciding vote against the American Health Care Act of 2017, which would have partially repealed the ACA. After being diagnosed with glioblastoma in 2017, he reduced his role in the Senate to focus on treatment, dying from the disease in 2018.

John Sidney McCain III was born on August 29, 1936, at Coco Solo Naval Air Station in the Panama Canal Zone, to naval officer John S. McCain Jr. and Roberta Wright McCain. He had an older sister, Sandy, and a younger brother, Joe. At that time, the Panama Canal was under U.S. control.

His father and his paternal grandfather, John S. McCain Sr., were also Naval Academy graduates and both became four-star admirals in the United States Navy. The McCain family moved with their father as he took various naval postings in the United States and in the Pacific. As a result, the younger McCain attended a total of about 20 schools. In 1951, the family settled in Northern Virginia, and McCain attended Episcopal High School, a private preparatory boarding school in Alexandria. He excelled at wrestling and graduated in 1954. He referred to himself as an Episcopalian as recently as June 2007, after which date he said he came to identify as a Baptist.

Following in the footsteps of his father and grandfather, McCain entered the United States Naval Academy, where he was a friend and informal leader for many of his classmates and sometimes stood up for targets of bullying. He also fought as a lightweight boxer. He earned the nickname "John Wayne" "for his attitude and popularity with the opposite sex." McCain did well in academic subjects that interested him, such as literature and history, but studied only enough to pass subjects that gave him difficulty, such as mathematics. He came into conflict with higher-ranking personnel and did not always obey the rules. "He collected demerits the way some people collect stamps." His class rank (894 of 899) was not indicative of his intelligence nor his IQ, which had been tested to be 128 and 133. McCain graduated in 1958.

McCain began his early military career when he was commissioned as an ensign, and started two and a half years of training at Pensacola to become a naval aviator. While there, he earned a reputation as a man who partied. He completed flight school in 1960, and became a naval pilot of ground-attack aircraft; he was assigned to A-1 Skyraider squadrons aboard the aircraft carriers USS Intrepid and USS Enterprise in the Caribbean and Mediterranean Seas. McCain began as a sub-par flier who was at times careless and reckless; during the early to mid-1960s, two of his flight missions crashed, and a third mission collided with power lines, but he received no major injuries. His aviation skills improved over time, and he was seen as a good pilot, albeit one who tended to "push the envelope" in his flying.