Adlai Ewing Stevenson II (February 5, 1900 – July 14, 1965) was an American politician and diplomat, noted for his intellectual demeanor, eloquent public speaking, and promotion of liberal causes in the Democratic Party. He served as the 31st Governor of Illinois, and received the Democratic Party's nomination for president in 1952 even though he had not campaigned in the primaries. John Frederick Martin says party leaders selected him "because he was more moderate on civil rights than Estes Kefauver, yet nonetheless acceptable to labor and urban machines—so a coalition of southern, urban, and labor leaders fell in behind his candidacy in Chicago."

Stevenson was defeated in a landslide by Republican Dwight D. Eisenhower in the 1952 presidential election. In 1956 he was again the Democratic presidential nominee against Eisenhower, but was defeated in an even bigger landslide. He sought the Democratic presidential nomination for a third time in the election of 1960, but was defeated by Senator John F. Kennedy of Massachusetts. After his election, President Kennedy appointed Stevenson as the Ambassador to the United Nations; he served from 1961 to 1965. He died on July 14, 1965 in London after suffering a heart attack.

The prominent historian Arthur M. Schlesinger, Jr., who served as one of his speechwriters, wrote that "Stevenson was a great creative figure in American politics. He turned the Democratic Party around in the fifties and made JFK possible...to the United States and the world he was the voice of a reasonable, civilized, and elevated America. He brought a new generation into politics, and moved millions of people in the United States and around the world." The journalist David Halberstam wrote that "Stevenson's gift to the nation was his language, elegant and well-crafted, thoughtful and calming." Willard Wirtz, his friend and law partner, once famously said "If the Electoral College ever gives an honorary degree, it should go to Adlai Stevenson."