Bastard!! Series 1-2
I started watching this series partly because of an interest in the heavy metal it was inspired by, and because like another series I'm keen on, Magic Knight Rayearth, it makes all sorts of references to other things. In Rayearth, which debuted in the 1990s, the manga referenced cars because CLAMP wanted to give everything a theme, and as cars had to be named well in order to be sold, they went with them. 1980s manga Bastard!!, whose subtitle is Heavy Metal - Dark Fantasy, references heavy metal because the artist was a fan of the genre, which a) makes more sense in terms of origins, and b) shows there is nothing new under the sun when it comes to such things. Bastard!! also makes some surprising anime references which I doubt were in the original manga. For example, a scene in the second series that references the Gurren Lagann "grit your teeth" punch is one I very much doubt was in the original source text, given that said volume appeared in 1992.
Aside from all the metal references (the lead character Dark Schneider's first spell is called "Venom", which I guess must be the first time a manga not only referenced black metal, but also a bunch of Geordies), I enjoyed the quality of the animation, and the plot did have many surprising twists and turns to it. Slightly less enjoyable was Dark Schneider's desire to seemingly have it off with every woman around him (good job his long hair covered the ladies nipples, as that we all know is the rudest thing you can possibly see), including the dark-elf who he adopted and acted as an adult to. Yes, somewhat creepy, but I do admit that that overall I still enjoyed the series, and if a third series comes out I'll probably watch it too. 8/10