Draygone Yarnes (Look for Boston Bruins)
Fiber N' Ice
Tricoterie (They have a Twilight yarn that's yellow & black)
Shelby's Yarns (Harry Potter Themed Yarns)
Dale of Norway: Baby Ull - True Black; Sunny
So you can scrounge through Ravelry, hunting, if you like them...
Harry Potter Opal Yarns