Yamana Sōzen (July 6, 1404 – April 15, 1473), is originally Yamana Mochitoyo before becoming a monk.

Due to his red complexion, he is sometimes known as Aka-nyūdō, "the Red Monk".

He is one of the daimyo who fights against Hosokawa Katsumoto during the Ōnin War in Kyoto.