François Pierre Guillaume Guizot (1787–1874) is a French historian, orator, and statesman.

Guizot is a dominant figure in French politics prior to the Revolution of 1848, a conservative liberal who opposes the attempt by King Charles X to usurp legislative power, and works to sustain a constitutional monarchy following the July Revolution of 1830.

He then serves the "citizen king" Louis Philippe, as Minister of Education, 1832–37, ambassador to London, Foreign Minister 1840–1847, and finally Prime Minister of France from 19 September 1847 to 23 February 1848.

Guizot's influence is critical in expanding public education, which under his ministry sees the creation of primary schools in every French commune.

But as a leader of the "Doctrinaires", committed to supporting the policies of Louis Phillipe and limitations on further expansion of the political franchise, he earns the hatred of more left-leaning liberals and republicans through his unswerving support for restricting suffrage to propertied men, advising those who want the vote to "enrich yourselves" (enrichissez-vous) through hard work and thrift.

As Prime Minister, it is Guizot's ban on the political meetings (called the Paris Banquets, which celebrate the birthday of George Washington) of an increasingly vigorous opposition in January 1848 that catalyzes the revolution that topples Louis Philippe in February and sees the establishment of the French Second Republic.

Guizot is famous as the originator of the quote "Not to be a republican at 20 is proof of want of heart; to be one at 30 is proof of want of head".

This quote has been reworked many times, especially in reference to socialism and liberalism.

It has been borrowed by or attributed to many notable figures who lived after Guizot, including Winston Churchill, George Bernard Shaw, Benjamin Disraeli, Georges Clemenceau, Otto von Bismarck, Aristide Briand, Theodore Roosevelt, Woodrow Wilson, David Lloyd George, Wendell Willkie, William J. Casey, and others.