[JediScum]

I don't know. I always thought "Rock Opera" was a story that was told with music. With metal, it seems like the term "concept album" was thrown around a lot, though.

But if "The Wall" and "Tommy" are rock opera, King Diamond's "Them" and "Conspiracy" should be included, as he would perform these albums live from start to finish, using props and sets.

Voivod's album "Dimesion Hatross", when reading the lyrics, is definitely a sci-fi story. Each of the 8 songs on that album furthers the story. What they did with it live, I don't know.

GWAR is probably a bad example. They would tell stories through the music, but not all songs on an album would be part of it.