Elves ~

"Small supernatural creatures who are now associated with Christmas through the notion that they work as Santa's helpers.
They were not always so benign.  They originated in [Scandinavia] -farm- or house-elves, who could be helpful if bribed but malicious if they were slighted, especially at Christmas when, as in Denmark, a bowl of milk must be left out for them.  In the second half of the 19th century, the reputation of elves began to change for the better as part of a drive to make Christmas more child-centred.  An 1859 poem in Harper's Weekly speaks of Santa Claus keeping "a great many elves at work,/ All working with all their might, / To make a million of pretty things..."

~ THE WORLD ENCYCLOPEDIA of CHRISTMAS, Gerry Bowler, McClelland & Stewart Ltd., 2000.