Old Hob
Baron
In British folklore fairies/elves can't touch iron. The 'good luck' you get from nailing an iron horseshoe above the door is that it keeps the little buggers out of your house.horseshoes keep faeries out in your part of the country?
The exception to the rule are the redcaps, a type of goblin from the Anglo-Scottish borders, who can not only touch iron, but have big iron boots (and dye their caps red by dipping them in human blood). Nasty so-and-sos.