The Adversary is the debut solo album of Emperor frontman Ihsahn. The album combines various elements from the different extreme metal genres, yet keeps the progressive edge from later Emperor works. It proves hard to categorize, due to the varied mix of styles incorporated, but in general the album is mainly rooted in progressive metal. Other styles mixed into this album include death metal, black metal, classic metal (in the vein of Iron Maiden, King Diamond and Mercyful Fate), symphonic metal, and on some tracks there is a strong thrash metal influence. Multiple songs have lines quoted from Friedrich Nietzsche's "Thus Spoke Zarathustra", and Ihsahn has cited this as a key thematic influence. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.