I'm not telling Amorphis or November's doom are like Katatonia. I Think the only band(i listened) nearly, are Rapture"Futile"cd. But that bands makes me feel in the same way, they have some "darkness"in his music. IS NOT THE SAME, BUT I THINK PEOPLE THAT LISTEN KATATONIA, CAN LISTEN THIS BANDS TOO, and find something near katatonia.It's the same with Opeth. They're not like katatonia, but have this "feeling" in his music. I don't know exactly how i can tell you better.
But maybe, i'm really wrong, i don't know...