Guy Henry Bullock (23 July 1887 – 1956) was a British diplomat who is best known for his participation in the 1921 British Mount Everest reconnaissance expedition. As expedition mountaineers, he and George Mallory found a northern access route to Everest by climbing the 6,849-metre (22,470 ft) Lhakpa La col above the East Rongbuk Glacier and by going on to reach the North Col at 7,020 metres (23,030 ft). They did not, however, reach the summit of Mount Everest.
Guy Bullock was born on 23 July 1887 in Beijing, the son of Thomas Lowndes Bullock, a member of the Radwinter branch of the Bullock family, and Florence Louisa Elizabeth Horton. Thomas Bullock was Professor of Chinese at Oxford University in 1899, and British Consul to China. Guy had an older sister.
Bullock was educated at Winchester College, where he was a member of the school's Ice Club along with Mallory who was his climbing partner. In 1905, he joined Mallory and the Winchester schoolmaster Graham Irving in the Pennine Alps where they reached the summit of the 4,356-metre (14,291 ft) Dent Blanche. In 1906, he played cricket for Winchester against Eton College.
Bullock was elected to the Alpine Club in 1909 at the early age of 22. In 1916 he married an American, Laura Alice McGlois (Alice).
Bullock had a 34-year career in the British Consular Service starting in 1913 when his first posting was to New Orleans to deal with British refugees from the Mexican Revolution. In 1914 he was sent to Fernando Pó where he organised operations against the German Cameroons in the run-up to World War I. By 1916 he was in Marseille and moved on to Lima in 1917. In 1922 he was posted to Le Havre, followed by Zagreb in 1926 and also to Addis Ababa. In 1935 he became British consul in Lyons. While posted to Ecuador (1938–1941), he climbed Cotopaxi and became the first person to take photographs of the crater. In 1944 he became Consul-General for French Equatorial Africa.