William Lewis Dayton (February 17, 1807 – December 1, 1864) was an American politician, active first in the Whig Party and later in the Republican Party.
In the 1856 presidential election, he became the first Republican vice-presidential nominee when nominated alongside John C.
Frémont.
The Republican Party lost that campaign.
During the American Civil War, Dayton served as the United States Ambassador to France, a position in which he worked to prevent French recognition of the Confederacy.