Norman Collie and the Big Grey Man (Am Fear Liath Mòr) of Ben Macdui

Ben Macdui rises to 1,309 m (4,295 ft) in the Cairngorms of Scotland. It is the second-highest mountain in the British Isles. In 1891 John Norman Collie climbed it alone.

He was returning from the cairn on the summit in mist. "I began to think I heard something else than merely the noise of my own footsteps. Every few steps I took I heard a crunch, and then another crunch, as if someone was walking after me but taking steps three or four times the length of my own."

He told himself it was nonsense. He could see nothing in the mist. The eerie crunch, crunch went on behind him, and he was seized with terror. He took to his heels, "staggering blindly among the boulders for four or five miles nearly down to Rothiemurchus Forest." He never saw a thing.

For more than thirty years the story waited. Then came late 1925. Collie was still eminent and active. At the 27th Annual General Meeting of the Cairngorm Club in Aberdeen, he told the room what had happened. His closing words have clung to the mountain ever since: "Whatever you make of it, I do not know, but there is something very queer about the top of Ben Macdui and I will not go back there again."

The Aberdeen Press and Journal printed the account. Letters followed. Some were doubtful, some offered explanations, and some came from people with similar experiences. In July 1926 the club's journal wrote it up as "The Ben Macdhui Giant Spectre."

Collie's footsteps became the heart of the legend of Am Fear Liath Mòr, the Big Grey Man. Dr A. M. Kellas and his brother Henry reportedly wrote to Collie about a figure at least as tall as the 10-ft-high cairn, walking out of the Lairig Ghru. In October 1943, the mountaineer Alexander Tewnion saw a shape that "loomed up, receded, came charging at me!" before he fired his revolver three times. In 1945 Peter Densham of RAF mountain rescue heard crunching footsteps at the summit cairn and felt an "inexplicable wave of uncontrollable fear."

Over ten feet tall and very thin, with dark skin and hair, long arms and broad shoulders. In the Spey Valley, the photographer John A. Rennie found prints 19 in long and 14 in wide. He later watched identical prints form as rain eroded the snow.

The debate began in those newspaper letters. They suggested the Spectre of the Brocken, falling stones, wind in the gullies, deer. A Brocken spectre is a walker's own shadow, cast huge on the mist, and it has fooled people here before. In 1791 the poet James Hogg saw "a giant blackamoor, at least thirty feet high." Then he watched it copy him taking off his hat. But a shadow explains a sighting better than it explains footsteps.

Others point to rock and ice cracking, disturbed wildlife, infrasound generated by the wind, exhaustion and isolation. On Skeptoid, Brian Dunning placed the legend among campfire stories, shaped by the natural fear people feel in fog and solitude. No source accuses Collie of inventing it.

Affleck Gray's The Big Grey Man of Ben MacDhui: Myth or Monster? appeared in 1970 and is still called the definitive study. When local stalkers were asked about it, the reply was short. "We do not talk about that."