Mori Motonari (?? ??, April 16, 1497 – July 6, 1571) was a prominent daimyo (feudal lord) in the western Chugoku region of Japan during the Sengoku period of the 16th century.
The Mori clan claimed descent from Oe no Hiromoto (????), an adviser to Minamoto no Yoritomo.
Motonari is known as a great strategist who began as a small local warlord (jizamurai) of Aki Province who extended his clan's power to nearly all of the Chugoku region through war, marriage, adoption and assassination.
Sandwiched between the powerful Amago and Ouchi clans, Motonari led the clan by carefully balancing actions and diplomacy.
Eventually, Motonari succeeded in defeating both and controlled the entire Chugoku region.
In his later years, he crushed the Otomo clan of Bungo Province in Kyushu.
Motonari ruled from Yoshida-Koriyama Castle, the clan's main bastion since the early 14th century.
His descendants became lords of the Choshu Domain.