Lionel Terray (25 July 1921, Grenoble, Isère – 19 September 1965) was a French climber who made many first ascents, including Makalu in the Himalaya (with Jean Couzy on 15 May 1955) and Cerro Fitzroy in the Patagonian Andes (with Guido Magnone in 1952).
A climbing guide and ski instructor, Terray was active in mountain combat against Germany during World War II. After the war, he became well known as one of the best Chamonix climbers and guides, noted for his speedy ascents of some of the most notorious climbs in the French, Italian, and Swiss Alps: the Walker Spur of the Grandes Jorasses, the south face of the Aiguille Noire de Peuterey, the north-east face of Piz Badile, and the north face of the Eiger. Terray, frequently with climbing partner Louis Lachenal, broke previous climbing speed records.
Terray was a member of Maurice Herzog's 1950 expedition to the Nepalese Himalayan peak, Annapurna, the highest peak climbed at the time, and the first 8000-meter peak climbed (although British climbers George Mallory, Andrew Irvine, George Finch, Geoffrey Bruce, Henry Morshead, Edward Norton and Howard Somervell had reached higher altitudes on Mount Everest during the 1920s). Terray did not reach the summit of Annapurna, but together with the Sherpa Adjiba he aided summitteers Maurice Herzog and Louis Lachenal down from the mountain. Both Herzog and Lachenal experienced extreme frostbite and subsequently underwent amputations.  Despite these events, the French team returned to Paris to huge public acclaim, and Herzog's expedition book Annapurna became an international bestseller.
Terray was also one of the main participants in the great attempt to rescue four climbers trapped on the north face of the Eiger in 1957. This mission forms the subject of Jack Olsen's famous book The Climb Up To Hell, in which Terray's skill and bravery receive special mention.
In the late 1950s and early 1960s, Terray made a number of first ascents in Peru, including the highest unclimbed peak in the central Andes at the time, 20,981-foot Huantsan. He also made first ascents of lower but more difficult peaks, including Willka Wiqi, Soray, Tawllirahu, and Chakrarahu, possibly the hardest peak in the Peruvian Andes and considered unclimbable at the time. One of Terray's finest achievements was the first ascent of 25,295-foot Jannu in Nepal in 1962. He also climbed the Nilgiris near Annapurna, and led the successful 1964 first ascent of 12,240 foot Mount Huntington, in the Alaska Range, by the northwest ridge. 
His grave is situated in Chamonix, France. A traffic circle is named for him in Chamonix, WSW of town.
- Terray, Lionel (1963). Les Conquérants de l'inutile. France: Victor Gollancz. ASIN B000HJRAVQ.
- Terray, Lionel; Geoffrey Sutton (trans.) (2000). Conquistadors of the Useless. Baton Wicks Publications; New Ed. ISBN 1-898573-38-7.