Sima Ang (died 205 BC) was the ruler of the Kingdom of Yin (殷國) of the Eighteen Kingdoms during the Chu–Han Contention, an interregnum between the Qin and Han dynasties of China.

Sima Ang originally served under the insurgent Zhao kingdom which emerged during the rebellions to overthrow the Qin dynasty in its final years. After the fall of the Qin dynasty in 206 BC, the former Qin Empire was divided into the Eighteen Kingdoms and Sima Ang was made the King of Yin, which covered parts of present-day northern Henan and southern Hebei provinces and capital at Zhaoge (present-day Qi County, Henan)

In 205 BC, Han Xin conquered the Kingdom of Yin for the Han dynasty and captured Sima Ang, who surrendered to Liu Bang, the founding emperor of the Han dynasty. The former Kingdom of Yin became the Henei Commandery of the Han Empire. Sima Ang died a month later at the Battle of Pengcheng between Liu Bang and his rival Xiang Yu.

Sima Ang's descendants founded the Jin dynasty (266–420).

• Sima, Qian. "Volume 7". Records of the Grand Historian.