François-Jean Lefebvre de la Barre (12 September 1745 – 1 July 1766) was a young French nobleman. He was tortured and beheaded before his body was burnt on a pyre along with Voltaire's Philosophical Dictionary nailed to his torso. La Barre is often said to have been executed for not saluting a Catholic religious procession, though other charges of a similar nature were laid against him.

In France, Lefebvre de la Barre is widely regarded a symbol of the victims of Catholic religious intolerance, along with Jean Calas and Pierre-Paul Sirven, all championed by Voltaire. A statue to de la Barre stands near the Basilica of the Sacred Heart of Jesus of Paris at the summit of the butte Montmartre (itself named from the Temple of Mars), the highest point in Paris and an 18th arrondissement street nearby the Sacré-Cœur is also named after Lefebvre de la Barre.

Lefebvre de la Barre was a descendant of Antoine Lefèbvre de La Barre, a governor of the French Antilles and then New France.