This question can be a bit more ambiguous than you realise. Out of all the band which played Death Metal, Sepultura would be it. However, none of the albums they released during their Death Metal period would be particularly high grossing albums. Out of straightforward, true-to-form Death Metal bands, who haven't deviated away from it, Cannibal Corpse would be the band. As for the so-called Melodeath bands, they're irrelevant.
Melodic Death Metal
Death Metal - split album - was created in 1984.
Indeed it is. especially melodic death metal!
Within the metal genre, "technical" death metal or "math metal" as a whole would be the most complex. Followed by progressive metal.
Swedish band Dark Tranquillity plays melodic death metal, also referred to as melodeath. Melodic death metal is a subgenre of heavy metal music, and was pioneered by bands Dark Tranquillity, At the Gates and In Flames in the early to mid-1990s.
Melodic death metal
Folk metal, melodic death metal, death metal, METAL.
No, Melodic Death Metal.
Not exactly melodic death metal as they are more black metal (stylistically melodic black metal) but Catamenia from Finland has featured wolves in almost every album cover (except for Calvacade) and feature an arctic sound akin to Sonata Arctica. Otherwise, I don't know any that really feature wolves to that extent. Not sure what you mean by "feature" but this could be correct.
Melodic Death Metal
Melodic Death Metal and Power Metal
melodic death metal
It would have to be melodic death metal as it is a bit more commercially accessible than the other genres with deathcore close behind and just recently maybe even defeating melodic death metal by a margin.
Death Metal - split album - was created in 1984.
Mainstream? very very low, death metal is too heavy for mainstream success. It's low with Mainstream (but mainstream media is far from most credible when It comes to actual media quality) With more legitimate brands of Death Metal born in recent years and not to mention Melodic Death Metal earning plenty of commercial success I'm gonna have to say Melodic Death Metal is doing quite well.
Indeed it is. especially melodic death metal!
Slipknot Slipknot are not 'death metal' they are nu metal. You want a 'death metal' band look into ABACABB, Nile or Job for a Cowboy. Also try The Black Dahlia Murder they are Melodic death metal.