[3] A band member, all of whom are referred to only as Nameless Ghouls, explained that the songs on Opus Eponymous were written in 2007 and 2008, around two years before the album was released.

[6] Forge contacted his former Repugnant bandmate Gustaf Lindström and recorded demos of "Stand by Him", "Prime Mover" and "Death Knell" in early 2008.

He approached several vocalists for the role, including Messiah Marcolin, Mats Levén, Christer Göransson of Mindless Sinner, and JB Christoffersson.

The musician later stated "that night, my whole life changed;" within two days of posting the demos, he was contacted by record labels from around the world.

[6] The album artwork is a reference to a promotional poster for the 1979 television miniseries adaption of Stephen King's 'Salem's Lot.

One Nameless Ghoul said "We did the whole thing with a standard Gibson SG", and explained they were limited as opposed to their second album, "which is why a lot of the guitars sound more traditionally metal.

[10] Describing why they covered "Here Comes the Sun", a Ghoul said "I've been a fan of Beatles even longer than I've been listening to hard rock, so it made a lot of sense.

"[11] He explained that the band selects songs to cover based on if they can adapt it into their own: "We sort of found the angle of taking that so and inverting it.

"[11] The theme of Opus Eponymous ties in with the band's second album, Infestissumam: "Everything on the first record was about a coming darkness, an impending doom.

[24] In the June 2011 edition of Sweden Rock Magazine it was named the third best album in the past decade, with the first two being The Final Frontier and A Matter of Life and Death by Iron Maiden.

[28] In 2015, Benjamin Hedge Olson of PopMatters called Opus Eponymous a 21st-century classic: "The production oozed spot-on early-'80s atmosphere, the lyrics were blatantly Satanic without being silly, and whomever Nameless Ghoul wrote those tracks was a master of hooks and melody.