Arguably my favourite area of black metal (along with psychedelic, an area certainly not exclusive to industrial, though much harder to define), the Industrial variety is something that has never made much headway, even in black metal circles. It tends to remain in disparate pools, rather than collating into any semblance of "scene" or "movement" or what have you. Personally I'd hate it if it became en vogue and started to (arguably) stagnate like the post-rock, blackgaze, atmo-black bands that are currently trending. Each entity is often unique and forced to define themselves by creative means. In terms of the fangled "atmosphere" that every blackened outfit purports to exude, industrial is by far the most appealing for me, doing away with trite evil and archaic visual themes in favour of an oppressive, mechanised terror, images of decay and post-apocalyptic dischord and themes of politics and philosophy.
And of course, gas masks.
Some favourites of the genre to follow in the first post....