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 , the lord of . By 1650, Spaen served as a Landdrost, a government councillor, and an Oberst (colonel), and he became the leader of a cavalry regiment the following year. In 1654 he captured Dietrich Karl zu Wylich-Winnenthal, the leader of an uprising against Elector Frederick William, and brought him to Spandau. Spaen led Prussia's Horse Guards (Leibregiment zu Pferde) during the Northern Wars, participating in the Battle of Warsaw. The colonel was restationed on the Lower Rhine in 1656. He became commander of Kalkar on 27 May 1657 and was promoted to Generalmajor the following year. On 25 May 1661, Spaen received the titl