Knud Ørn Bryn (15 March 1855 – 28 May 1941) was a Norwegian engineer and industrialist.

He was one of the pioneers in the development of modern hydropower plants in Norway.

He was the son of Thomas Bryn (1813-1902) and Kristine Emilie Caroline Richter (1825-1869).

In 1898, he established Hafslund ASA the company which operated the power grid supplying electricity to Oslo.

Bryn was chairman from 1929 to 1936 of AS Tyssefaldene, a power company supplying power to energy-intensive industrial companies in Odda, the main commercial and economic centre of the region of Hardanger.