Wendell Lewis Willkie (born Lewis Wendell Willkie; February 18, 1892 – October 8, 1944) was an American lawyer, corporate executive and the 1940 Republican nominee for president of the United States. Willkie appealed to many convention delegates as the Republican field's only interventionist: although the U.S. remained neutral prior to Pearl Harbor, he favored greater U.S. involvement in World War II to support Britain and other Allies. His Democratic opponent, incumbent President Franklin D. Roosevelt, who had made campaign pledges against U.S. involvement in World War II, won the 1940 election with about 55% of the popular vote and took the electoral college vote by a wide margin.

Willkie was born in Elwood, Indiana, in 1892; both his parents were lawyers, and he also became one. He served in World War I but was not sent to France until the final days of the war, and saw no action. Willkie settled in Akron, Ohio, where he was initially employed by Firestone, but left for a law firm, becoming one of the leaders of the Akron Bar Association. Much of his work was representing electric utilities, and in 1929 Willkie accepted a job in New York City as counsel for Commonwealth & Southern Corporation (C&S), a utility holding company. He was rapidly promoted, and became corporate president in 1933. Roosevelt was sworn in as U.S. president soon after Willkie became head of C&S, and announced plans for a Tennessee Valley Authority (TVA) that would supply power in competition with C&S. Between 1933 and 1939, Willkie fought against the TVA before Congress, in the courts, and before the public. He was ultimately unsuccessful, but sold C&S's property for a good price, and gained public esteem.

A longtime Democratic activist, Willkie changed his party registration to Republican in late 1939. He did not run in the 1940 presidential primaries, but positioned himself as an acceptable choice for a deadlocked convention. He sought backing from uncommitted delegates, while his supporters—many youthful—enthusiastically promoted his candidacy. As German forces advanced through western Europe in 1940, many Republicans did not wish to nominate an isolationist like Robert A. Taft, or a non-interventionist like Thomas E. Dewey, and turned to Willkie, who was nominated on the sixth ballot. Willkie's support for aid to Britain removed it as a major factor in his race against Roosevelt, and Willkie also backed the president on a peacetime draft. Both men took more isolationist positions towards the end of the race. Roosevelt won an unprecedented third term, taking 38 of the 48 states.

After the election, Willkie made two wartime foreign trips as Roosevelt's informal envoy, and as nominal leader of the Republican Party gave the president his full support. This angered many conservatives, especially as Willkie increasingly advocated liberal or internationalist causes. Willkie ran for the Republican nomination in 1944, but bowed out after a disastrous showing in the Wisconsin primary in April. He and Roosevelt discussed the possibility of forming a liberal political party after the war, but Willkie died in October 1944 before the idea was finalised. Willkie is remembered for giving Roosevelt vital political assistance in 1941, which helped the president to pass Lend-Lease to send supplies to the United Kingdom and other Allied nations.

Lewis Wendell Willkie was born in Elwood, Indiana, on February 18, 1892, to Henrietta (Trisch) and Herman Francis Willkie. Both of his parents were lawyers, his mother being one of the first women admitted to the Indiana bar. Willkie was the fourth of six children, all intelligent, and learned skills during the nightly debates around the dinner table that would later serve him well.

Although given the first name Lewis, Willkie was known from childhood by his middle name. Herman Willkie, who had come from Prussia with his parents at age four, was intensely involved in progressive politics, and in 1896 took his sons to a torchlight procession for Democratic presidential candidate William Jennings Bryan, who had come to Elwood during his campaign. The Willkie boys had a sidewalk fight with Republican youths, and though the Willkies won their battle, Bryan lost his to William McKinley. When Bryan ran again in 1900, he stayed overnight at the Willkie home, and the Democratic candidate for president became the first political hero for the boy who would later seek that office.

By the time Willkie reached age 14 and enrolled in Elwood High School, his parents were concerned about a lack of discipline and a slight stoop, and they sent him to Culver Military Academy for a summer in an attempt to correct both. Willkie began to shine as a student in high school, inspired by his English teacher; one classmate said that Philip "Pat" Bing "fixed that boy up. He started preaching to Wendell to get to work and that kid went to town." Faced with a set of athletic brothers—Edward became an Olympic wrestler—Willkie joined the football team but had little success; he enjoyed the debate team more, but was several times disciplined for arguing with teachers. He was class president his final year, and president of the most prominent fraternity, but resigned from the latter when a sorority blackballed his girlfriend, Gwyneth Harry, as the daughter of immigrants.

During Willkie's summer vacations from high school, he worked, often far from home. In 1909, aged 17, his journey took him from Aberdeen, South Dakota, where he rose from dishwasher to co-owner of a flophouse, to Yellowstone National Park, where he was fired after losing control of the horses drawing a tourist stagecoach. Back in Elwood, Herman Willkie was representing striking workers at the local tin plate factory, and in August journeyed with Wendell to Chicago in an attempt to get liberal attorney Clarence Darrow to take over the representation. They found Darrow willing, but at too high a price for the union to meet; Darrow told Wendell Willkie, "there is nothing unethical in being adequately compensated for advocating a cause in which you deeply believe."