Saint Kessog was an Irish missionary of the mid-sixth century active in the Lennox area and southern Perthshire. Son of the king of Cashel in Ireland, Kessog is said to have worked miracles, even as a child. He left Ireland and became a missionary bishop in Scotland. Using Monks' Island in Loch Lomond as his headquarters, he evangelized the surrounding area until he was martyred, supposedly at , where a heap of stones was known as St Kessog's Cairn. Kessog was killed in 520 AD. The Kessock area of Inverness is named after the saint, as is the Kessog oil field in the North Sea.