6 January] 1769 – 11 June 1843), better known as Peter Wittgenstein in English, was a prince of the German dynasty of Sayn-Wittgenstein and field marshal in the Imperial Russian Army during the Napoleonic Wars.

Born Ludwig Adolf Peter Graf zu Sayn-Wittgenstein-Ludwigsburg-Berleburg, he was descended from a family of ruling German Counts whose seat was in Berleburg (present day North Rhine-Westphalia, Germany).

His parents were Count Christian Louis Casimir of Sayn-Wittgenstein-Ludwigsburg and his first wife, Countess Amalie Ludowika Finck von Finckenstein (1740–1771).

The fighting at Polotsk decided the fate of Saint Petersburg and earned Wittgenstein the title of "Saviour of Saint-Petersburg".

In 1834 King Frederick William III of Prussia granted him the title of Fürst (Prince) zu Sayn-Wittgenstein.