Well what kind of death metal fans are they? Are they fans of the old school kind or the more recent deathcore, brutal death or technical death kind?
Older opeth material is a good example of progressive death metal. However they gradually drifted away from death metal and became something that is not really death.
First there is the wondrous website metal archives:
http://www.metal-archives.com/
Feel free to get on the forum and check the threads about the different kinds of metal.
To really begin getting in touch with death metal you also need to start the beginning. I think you know deep purple, black sabbath and iron maiden but the first real step was done by
venom Also called the first extreme metal band. Venom were very important in creating thrash and eventually death and black metal.
The next important band is
Celtic Frost They were important in the development of the new vocal style and riffing. Other good examples of this era are Slayer and Kreator
Following celtic frost and other early thrash bands in 1985 the first more death metal than thrash album was released,
Seven Churches by Possessed. Their later work was more heavy thrash.
However possessed were still clearly very thrashy. A couple of the major bands that caused the definite split of death from thrash were
Death,
Morbid Angel,
Obituary and Master. Around 89 the basic form of old school floridan death metal was set. Ofcourse the development didnt end there but continued both in the US and other places all over the world.
The most important country for death metal together with the US is arguably Sweden. For such a little country Sweden produced tons and tons of death metal bands with its own style. simply named Swedish death metal. It differs from other scenes mostly in being more melodic and more crust punk influenced. The most important of these were
Nihilist which then changed into Entombed Dismember Unleashed and
Grave
Death metal quikly diversed into a couple of extra ways of playing. These are being Grindcore influenced:
Napalm death. Brutal death metal:
Suffocation and Technical:
Hellwitch and
Disincarnate
This was all during the prime period of classic death metal from 1989 till around 94. After 1994 the death metal scene sort of collapsed in popularity, especially in the US.
However innovation in the genre didnt stop there. Sweden went on to produce more melodic death metal like
At The Gates and
In Flames
In other countries avant garde death metal came up with for example the classic
Obscura by Gorguts and
Nespithe by Demilich. However more during the same time also more "conventional" progressive death metal came up like Opeth.
Death metal however still used to be kinda just crawling allong except for a few excellent releases. However from about 1998 the genre started getting back in strength. Melodic death metal exploded in world wide popularity. Technical death metal got gradually more and more popular especially of the extra technical kind like
Necrophagist and
Origin and more brutal death, about which i dont know much in its modern form.
The latest development in this genre is Deathcore. Which basically is metalcore with less melodic death influence but with more normal especially brutal death influence. Quite allot of fans of the older kinds of death metal dont like deathcore at all(me being one of them) but key examples of this genre are
Despised Icon and
Job for a Cowboy
That is about it.