Countess Emilia Plater (Broel-Plater, Lithuanian: Emilija Pliateryte; 13 November 1806 – 23 December 1831) was a noblewoman and revolutionary from the lands of the partitioned Polish–Lithuanian Commonwealth.
Raised in a patriotic tradition in Liksna near Daugavpils, she fought in the November Uprising of 1830–1831 against the Russian Empire.
She raised a small unit, participated in several engagements in present-day Lithuania, and received the rank of captain in the Polish insurgent forces.
When the main forces under the General Dezydery Chlapowski decided to cease fighting and cross into Prussia, Plater vowed to continue the fight and wanted to cross into Poland where the uprising was still ongoing.
However, she fell ill and died.
Though she did not participate in any major engagement, her story became widely publicized and inspired a number of works of art and literature.
A maiden warrior, she is a national heroine in Poland and Lithuania.
She has been venerated by Polish artists and by the nation at large as a symbol of women fighting for the national cause.
She is often referred to as the "Lithuanian Joan of Arc".