Countess Anne of Nassau-Siegen, German: Anne Gräfin von Nassau-Siegen, official titles: Gräfin zu Nassau, Vianden und Diez, Frau zu Breda, was a countess from the House of Nassau-Siegen, a cadet branch of the Ottonian Line of the House of Nassau, and through marriage successively Duchess of Brunswick-Lüneburg and Countess of Katzenelnbogen. She acted as regent of the Duchy of Brunswick-Lüneburg for her son in the period 1479–1486.

Philipp I of Katzenelnbogen (1402–1479), also known "Philipp the Elder" was Count of Katzenelnbogen from 1444 to 1479 and was the last male descendant of the Counts of Katzenelnbogen. His parents were Johann IV, Count of Katzenelnbogen and Anne of Katzenelnbogen, who merged the two lines of the family back together in 1402.