Demon of Loch Ness

On August 22, 564, the St. Columba famously encountered a water demon in the River Ness in Scotland. Cryptozoologists and various authors claim this 6th century account was the first sighting of the Loch Ness monster. However, there are several notable differences on how the water demon was portrayed vs the sightings of Loch Ness Monster, whose name was first applied to the creature in 2 May 1933.

6th Century Account
In Adomnán's the Life of St. Columba, Founder of Hy, the creature is referred to as an unholy water beast that was exorcised by St. Columba. "ON another occasion also, when the blessed man was living for some days in the province of the Picts, he was obliged to cross the river Nesa (the Ness); and when he reached the bank of the river, he saw some of the inhabitants burying an unfortunate man, who, according to the account of those who were burying him, was a short time before seized, as he was swimming, and bitten most severely by a monster that lived in the water; his wretched body was, though too late, taken out with a hook, by those who came to his assistance in a boat. The blessed man, on hearing this, was so far from being dismayed, that he directed one of his companions to swim over and row across the coble that was moored at the farther bank. And Lugne Mocumin hearing the command of the excellent man, obeyed without the least delay, taking off all his clothes, except his tunic, and leaping into the water. But the monster, which, so far from being satiated, was only roused for more prey, was lying at the bottom of the stream, and when it felt the water disturbed above by the man swimming, suddenly rushed out, and, giving an awful roar, darted after him, with its mouth wide open, as the man swam in the middle of the stream. Then the blessed man observing this, raised his holy hand, while all the rest, brethren as well as strangers, were stupefied with terror, and, invoking the name of God, formed the saving sign of the cross in the air, and commanded the ferocious monster, saying, "Thou shalt go no further, nor touch the man; go back with all speed.""