It's not really ambient, but you might enjoy Elaine Radigue's music, particularly "Trilogie de la Mort", "Arthesis", and "Geelriandre".

You also might want to try drone bands like Earth, Sunn O))), and some Boris.

Almost anything by Stijn van Cauter; Cold Aeon, Dreams Of Dying Stars, Tear Your Soul Apart, I Dream No More.

Most of his other projects are Drone Doom, like Earth and Sunn 0))) mentioned above, which is an offshoot of Doom Metal.

Edit: You might also want to try Voice Transmissions With the Deceased, Gray Field Recordings (my personal favorite), Lord Wind, and from what I hear Nadja is very good also.

glad to see someone bringing up Aidan Baker's side project. I have the majority of his solo albums under his real name and I absolutely would recommend them to anyone!

Matt Borghi "Tracing Spaces- Minimal Ambient Guitar- An Anthology" [album]

Hum of the Druid - Wall of Arms

When I first heard it it went by without leaving a trace. When I listened to it a second time it suddenly came alive for me! One of my all-time favourites.

Thanks, this is really good

Dilate "Octagon"

Necrophorus "Elinros"

NP: Lustmord - Carbon Core