Father Charles Edward Coughlin (October 25, 1891 – October 27, 1979) was a Roman Catholic priest from Royal Oak, Michigan, a priest from Shrine of the Little Flower Catholic Church, and one of the first evangelists to preach to a widespread listening audience over the medium of radio during the Great Depression. He began his radio broadcasts in 1926, broadcasting weekly sermons on a regular program. He was an early supporter of the reforms of Franklin D. Roosevelt, and the author of the phrase "Roosevelt or ruin," which was famous during the early days of the FDR administration. However, Coughlin's theology changed over the course of the 1930s as he preached more and more about "monetary reform" and the influence of "international bankers" and upon the welfare of the United States. Coughlin fought strongly for the nationalization of banks.

Coughlin endorsed Franklin D. Roosevelt during the 1932 Presidential election. However, by 1935, Coughlin had begun to oppose Roosevelt's policies. In that year, he founded the National Union for Social Justice , an organization with a strong following among proponents of nativism and inflation, especially in the Midwest. Coughlin's organization also appealed to Irish Catholics living in the cities. By 1936, Coughlin had become a bitter critic of the Roosevelt administration. In 1936, Coughlin helped found a short-lived political party, the Union Party, which nominated William Lemke for President.

After 1936, Coughlin increasingly expressed support for the fascist policies of Hitler and Mussolini as an antidote to Bolshevism, though this was before World War II began, and his radio broadcasts became overtly anti-Semitic. He also began publication of a newspaper, Social Justice, during this period, in which he printed anti-Semitic accusations such as the Protocols of the Elders of Zion. In 1940, church authorities ordered Coughlin to stop his radio broadcasts and return to his duties as a parish priest.

At its peak, his radio show was phenomenally popular: historians state that his office received 80,000 letters per week from listeners. His listening audience was estimated to be as much as one-third of the nation. The political power of his radio show did not go unnoticed, and Coughlin was often grouped together with other radio speakers under the political umbrella of the "lunatic fringe." His listening audience did have the power to change the sway of elections, and Coughlin is often credited as one of the major demagogues of the 20th century for being able to influence politics through a wide audience, without actually holding a political office himself.