The term Muscadin (French: [myskadɛ̃]), meaning "wearing musk perfume", came to refer to mobs of young men, relatively well-off and dressed in a dandyish manner, who were the street fighters of the Thermidorian Reaction in Paris in the French Revolution (1789-1799). After the coup against Robespierre and the Jacobins of 9 Thermidor Year II, or 27 July 1794, they took on the remaining Jacobins and sans-culottes, and largely succeeded in suppressing them over the next year or two. In prints they are often seen carrying large wooden clubs, which they liked to call "constitutions". They were supposedly organized by the politician and journalist Louis-Marie Stanislas Fréron, and eventually numbered 2,000-3,000. They, in fact, seem to have mostly consisted of the lower middle classes, the sons of "minor officials and small shopkeepers", and were quietly encouraged by the shaky new government, who had good reason to fear Jacobin mobs, and wider unrest as the hard winter of 1794-5 saw increasing hunger among the Parisian working class. The Muscadins are considered to be part of the First White Terror in response to the preceding Reign of Terror of the Jacobins.

The "jeunesse dorée" came to have a considerable influence on the National Convention, and after the Jacobin revolt of 12 Germinal, Year III (April 1, 1795), are held to have forced the arrest of the four main "ringleaders" remaining from the Jacobin regime: Bertrand Barère, Jacques-Louis David, Jean-Marie Collot d'Herbois and Jacques Nicolas Billaud-Varenne, who were all threatened with transportation to French Guiana (though only the latter two were eventually sent there). After they had succeeded in suppressing the sans-culottes, their usefulness to the government was over, and they began to pose a threat. After the "whiff of grapeshot" in the crisis of 13 Vendémiaire, in October 1795, they ceased to be a significant factor in Parisian politics.