Ol' Fortune can be found on Mt. Middleton Summit, he can also be freed from the Crank-a-kai with a Green coin
Receiving food (favorite): "Mmm... so rich..."
Loafing: "I need a nap."
Freed from Crank-a-Kai: "So clever to get me out... I think you'll want me on your side."
In room C-301 of Tranquility Apartments (Shopper's Row), a non-hostile Ol' Fortune will give Crank-a-kai coins in exchange for rare bugs and fish.
Ol' Fortune might be based on Father Christmas, the English folkloric figure that represents the cheer and revelry of winter festivities, which during the 19th century was conflated with the Greek saint called Nikolaos of Myra (Saint Nicholas), who was worshipped by non-Catholic Christians and known for secret gift-giving. Father Christmas typically donned green or scarlet fur robes, which became red when his image evolved into the modern Santa Claus (see Ol' Saint Trick#Origin).
All of this is likely combined with Fukurokuju, one of the Seven Lucky Gods. A former sennin (hermit who has transcended mortal human status through ascetic practices) and the god of happiness, wisdom and long life, he's portrayed as an old man with long, white facial hair and an unusually tall forehead, accompanied by a crane and a turtle, two animals that represent longevity.
"Fukuro-jijii" translates roughly as bag-carrying grandpa, while sounding close to "Fukurokuju".