The Lycée Louis-le-Grand (French pronunciation: ​[lise lwi lə gʁɑ̃]), also referred to simply as Louis-le-Grand or by its acronym LLG, is a public Lycée (French secondary school, also known as sixth form college) located on rue Saint-Jacques in central Paris. It was founded in the early 1560s by the Jesuits as the Collège de Clermont, was renamed in 1682 after King Louis XIV ("Louis the Great"), and has remained at the apex of France's secondary education system despite its disruption in 1762 following the suppression of the Society of Jesus. It offers both a high school curriculum, and a Classes Préparatoires post-secondary-level curriculum in the sciences, business and humanities.

The admission process is based on academic grades, drawing from middle schools (for entry into high school) and high schools (for entry into the preparatory classes) throughout France. Its educational standards are highly rated and the working conditions are considered optimal, owing to a demanding recruitment of teachers. Louis-Le-Grand's students, occasionally referred to as magnoludoviciens, regularly top national rankings for baccalauréat grades (high school), number of Concours général laureates and entry into the grandes écoles (preparatory classes).