Where Did the Willies Come From?

I just watched a commercial on TV for a retirement home in Illinois. I'm not sure why, but it gave me the willies - which led me to check on its spelling. Which, in turn, led me to a story from the Brothers Grimm. Which, in turn, led me to learn the history behind the word "willie."

According to Heinrich Heine (German legend), the “Wilis” are “maidens who have died before their wedding day, because of faithless lovers.” They rise from their tombs at night to seek vengeance, and if any man is unlucky enough to encounter them, he is forced to dance till he drops dead from exhaustion.