Sir Arnold Henry Moore Lunn (18 April 1888 – 2 June 1974) was a skier, mountaineer and writer. He was knighted for "services to British Skiing and Anglo-Swiss relations" in 1952. His father was a lay Methodist minister, but Lunn was an agnostic and wrote critically about Catholicism before he converted to Catholicism at the age of 45 and became a Catholic apologist.
He was born in Madras, India and died in London.
Arnold Lunn's father, Sir Henry Simpson Lunn (1859–1939), was firstly a Methodist minister and later founder of Lunn's Travel agency (that would become Lunn Poly), which encouraged tourism in the Swiss Alps. Arnold Lunn's brother, Hugh Kingsmill Lunn, became a noted literary journalist under the name Hugh Kingsmill. Lunn attended Orley Farm School, in Harrow, followed by Harrow School. He studied at Balliol College, Oxford, and while he was there, founded and was sometime President of the Oxford University Mountaineering Club.
Introduced to skiing by his father, he invented the slalom skiing race in 1922. Mathias Zdarsky had been running competitions through poles in the early years of the 20th century, but they were essentially style competitions, though they had to be completed within a specified time. In 1921 Lunn organized the first British national ski championship to include a national slalom race as well as jumping and cross-country. The 1921 slalom was decided on style, as Zdarsky's pole race had been. By 1922, however, Lunn, convinced that there was a real need for a race designed to test a skier's ability to turn securely and rapidly on steep Alpine ground, was insisting on speed being the only arbiter. "The object of a turn is to get round a given obstacle losing as little speed as possible," he wrote. "Therefore, a fast ugly turn is better than a slow pretty turn." On 1 January 1922, the Alpine Ski Challenge Cup, first held in 1920, was transformed into a challenge cup for slalom racing. On the practice slopes at Mürren, Lunn set pairs of flags through which the competitors had to turn, and the flags were so set as to test the main varieties of Alpine ski turns. Lunn's innovation was that the winner was simply the competitor who could make his way down in the shortest time. This first slalom was won by J. A. Joannides.