Problems with originality

[Voldermort]

I would base them on someone you know, if it's possible. Basically the same as you're doing, but nobody will recognise that person because only you know them.

[Spring-Gem]

Every reader will imagine your characters differently than you do unless your descriptions are very detailed which is also quite boring. Describe your characters' appearances in general terms. If you describe a typical elf as tall, blonde haired, and blue eyed, you might imagine Legolas, but I might imagine Haldir. I think the only time physical descriptions matter is something that affects the story, for example a scar and how that affects and shapes the character within the story.