Valdemar and Voldemort

Another addition to last night's discussion: we talked a bit about the name "Voldemort" and I mentioned the similar "Valdemar" but again couldn't remember where I'd heard it. I searched around a little and came across the short story "The Facts in the Case of M. Valdemar." This horror story by Poe is about a man who is put into a hypnotic state just before his death with pretty gruesome results - a warning about trying to control/prevent/master death if I've ever heard one (this will make more sense when we reach the later HP books). There were also quite a few Scandinavian nobles (mostly Danish) with the name Valdemar during the Middle Ages, although none of them jump out at me as being relevant here.