Alexander Freiherr von Spaen (14 January 1619 – 23 October 1692) was a Generalfeldmarschall of Brandenburg-Prussia. Spaen was born in the Duchy of Cleves as the son of Bernhard von Spaen, the lord of Kreuzfort. Spaen was married three times: with Hendrine von Arnheim (died 4 August 1671); with Johanna Dorothea Quadt von Wyckerath-Soppenbroich (died 4 September 1676); and with Dorothea von Flemming.