The Gathering 'Mandylion' is a perfect example of an amazing,heavy atmospheric album with IMO the best female vocals ever. Favorite songs would be 'Eleanor' and 'Strange Machines'
Atrox. Awesome progressive music with an excellent and completely unique female vocalist......none of the "goth" or "symphonic" stuff that's generally the cliche band with female vocals.
Liv Kristine Espenaes formerly of Theater of Tragedy is a killer vocalist. Her new band Leaves Eyes are really good the first release Lovelorn is excellent. Also the 2nd record record Vinland Saga is good also.
Then there is The Gathering- Night Time Birds is one of their best and Sleepy Builinds is really good as well.
For growls, I would go with The frontman (well, frontwoman) of the Japanese band Shadow; Tokiko Shimamoto. She's one of the best death metal vocalists I've ever heard. Male OR female.
And someone mentioned it already, but for clean vox, Within Temptation is the way to go.