Sir Quackly was an 11th century leader of Clan McDuck. In the civil war between Macbeth, King of Scotland (reigned 1040-1057) and Malcolm III Canmore (reigned 1058-1093), Quackly chose to fight for the former. To assure hiscontinued loyalty, Macbeth rewarded him with a small fortune in gold. Quackly became obsessed with guarding his new chest of treasure. He had a secret crypt built within the walls of Dismal Downs, the ancestral castle of the Clan. He placed his treasure there and checked on it oftenly. By accident he was locked within the crypt and died of asphyxiation with his treasure at hand. The McDucks failed to locate their leader and the treasure after centuries of searching for it. The ghost of Quackly was rumored to be guarding the treasure.
In the story "Old Castle's Secret" (1948), Scrooge McDuck locates the remains of Quackly and the treasure using an X-Ray machine. In the "Life and Time of Scrooge McDuck", the ghost of Quackly appaers to offer advice to young Scrooge from time to time. Scrooge having no idea the old gentleman is a ghost.