Am Fear Liath Mòr

[3] Tangible evidence of its existence is limited to a few photographs of unusual footprints, so the majority relies on the credibility of eyewitness encounters.

Unlike the Am Fear Liath, Brenin Llwyd is found in mountainous locations across Wales, and is particularly noted to prey on children.

A noted hiker, professor, and member of the Royal Geographical Society, Collie recounted a terrifying experience he had as he hiked alone near the summit of Ben Macdui years earlier in 1891.

One climber, Hugh D. Welsh, said that he hiked the summit with his brother in 1904, where throughout the day and night they heard "slurring footsteps, as if someone was walking through water-saturated gravel."

One afternoon, just as I reached the summit cairn of Ben MacDhui, mist swirled across the Lairig Ghru and enveloped the mountain.

The atmosphere became dark and oppressive, a fierce, bitter wind whisked among the boulders, and... an odd sound echoed through the mist – a loud footstep, it seemed.

[9] An optical illusion known as the Brocken spectre is a plausible explanation for some visual elements of the Big Grey Man legend.

[12] The poet James Hogg encountered a Brocken spectre on Ben MacDui as far back as 1791, describing "a giant blackamoor, at least thirty feet high, and equally proportioned, and very near me.

[3][6] British mountaineer Frank Smythe stated he had observed his shadow cast as a Brocken spectre across the mist on Ben Macdhui as well.