Well, any guitar can be used for any kind of music, but certain types are gravitated to for various styles...
Anyway, "metal" guitars usually atleast have a bridge humbucker, flat fret board (usually with 24 frets). Floyd Rose type tremlos and pointy forms often acompany those features.
Depending on your playing style, you could just put a nice hot pickup in your bridge position and there you go, heavy metal guitar. My strat has all single coil pickups, and it has the sufficent "thickness" of tone to play metal. Anyway, just shop around, and see what you like.