Demchugdongrub, Mongol prince and politician, head of state of Mengjiang (died 1966)

Demchugdongrub, also known as Prince De, courtesy name Xixian, was a Qing dynasty Chinese Mongol prince descended from the Borjigin imperial clan who lived during the 20th century and became the leader of an independence movement in Inner Mongolia. He was most notable for being the chairman of the pro-Japanese Mongol Military Government (1938–39) and later of the puppet state of Mengjiang (1939–45), during the Second Sino-Japanese War. In the modern day, some see Demchugdongrub as a Mongol nationalist promoting Pan-Mongolism, while others view him as a traitor and a pawn of the Japanese during World War II.

Mengjiang, also known as Mengkiang, officially the Mengjiang United Autonomous Government, was an autonomous zone in Inner Mongolia, formed in 1939 as a puppet state of the Empire of Japan, then from 1940 being under the nominal sovereignty of the Reorganized National Government of the Republic of China. It consisted of the previously Chinese provinces of Chahar and Suiyuan, corresponding to the central part of modern Inner Mongolia. It has also been called Mongukuo or Mengguguo. The capital was Kalgan, from where it was under the nominal rule of Mongol nobleman Demchugdongrub. The territory returned to Chinese control after the defeat of the Japanese Empire in 1945.

February 8 is the 39th day of the year in the Gregorian calendar; 326 days remain until the end of the year.