Gackt is Alucard

In his debut Mizérable mini-album, the "Mizérable" music video, the photobook Mizérable ~Hishou~, and an early SHOXX article, Gackt is shown wearing a costume very similar to that of Alucard, the half-human, half-vampire son of Dracula from the video game Castlevania: Symphony of the Night (published by KONAMI). 
Here are some distinct similarities between the two (numbered in comparison image above)

1. Platinum blonde hair
2. Long black cloak - while the lining of Alucard's cloak is gray in the illustration, it stands to note that Alucard wears a cloak with red lining in the video game.
3. The design of the gold edging and buttons on the front and sleeves of Gackt and Alucard's outer jackets are almost exactly identical.
4. Gackt is wearing all the upper parts of Alucard's costume: outer coat, inner coat, and a white dress shirt.
5. Shiny black pants - this is not readily visible in the photo of Gackt, but his pants appear to be made of leather or PVC faux leather.
6. Shiny black high-heeled boots - this is also not readily visible in Gackt's photo, but Gackt also has the flaps at the tops of his boots, though the flaps are black instead of white.
7. Black gloves
8. Silver clasp and chain on cloak (see inset for detail - Alucard on left, Gackt on right)