Here's a few I enjoy greatly:
Archon Satani, Asche, Asmorod, Christoph Heemann, Desiderii marginis, Endura, Instincts, Kammarheit, Northaunt, Kurotokage, Necrophorus, Raison D'Etre, Sophia, Steve roach, Vinterriket, and Vidna Obmana
All of these bands make some quality dark ambient music. Check...