Byron Brenan CMG, (7 December 1847 – 28 February 1927), was a British diplomat who served in China from 1866.

One of his nephews John Fitzgerald Brenan was also a diplomat who also served as same British Consul General in Shanghai from 1930 to 1937.

Brenan joined UK Foreign Office in 1866 and served initially in Guangzhou, Shanghai, Beijing, Wuhu and Tianjin.

From 1893 to 1898 while serving as the British Consul General in Guangzhou, Brenan had to deal with response to rumours concerning the bubonic plague in Hong Kong and Sun Yat-sen's anti-Qing revolutionary movement.

In 1899, he successfully negotiated with the Qing court to expand the total area of Shanghai International Settlement by more than three times its size to 33,503 acres.