Anna of Nassau-Dillenburg (c. 1441–1514) was a Flemish-German philanthropist.
Anna was the eldest daughter of John IV, Count of Nassau-Dillenburg, and his wife Maria, the daughter of John II, Count of Loon-Heinsberg. Anna was married firstly (1467) to Otto V 'the Magnanimous,' Duke of Brunswick-Lüneburg. With Otto's early death (1471), her father-in-law, the elderly Duke Frederick acted as guardian of her son, Duke Henry I (1468–1532). Anna remarried (1474) to Philip I, Count of Katzenelnbogen (1402–1479), as his second wife, and went to reside under his roof. After Philip's death, the duchess returned to Celle in Brunswick, where she was appointed as guardian to her son after the death of his aged grandfather. Anna founded and established the hospital of St Anne in the suburbs of the town of Celle. She died there aged 72 on 8 April 1514.
Anna of Nassau-Dillenburg (21 September 1541 in Dillenburg – 12 February 1616 in Weilburg) was a daughter of Count William "the Rich" of Nassau-Dillenburg and his second wife, Juliana of Stolberg.
She married Count Albert of Nassau-Weilburg and had the following children: