What is the work?
The Darkest of the Hillside Thickets is a rock band situated in Chilliwack, British Columbia, Canada. The band is notorious for its references to the late H. P. Lovecraft's Cthulhu Mythos. In their 2007 album The Shadow Out of Tim, a marine biologist gets possessed by an alien intelligence known as a Yith, and learns things that man was not meant to know.
Who is the candidate?
Nyarlathotep, the Crawling Chaos. Nyarlathotep is responsible for every atrocity and horrific event that befalls on mankind ("Tumult and time bent/Mutilation and death in every land/Unleashing fear, creeping downward"). Nyarlathotep is described as taking on the form of man of darkness with evil, bloody secrets, a Black Pharaoh. He gives Tim the book of the dead (which is explicitly implied to be the Necronomicon) and Tim learns everything from it. He learns about how Nyarlathotep is not only responsible for practically every evil there is, but that he was the messenger who served other eldritch beasts from the Great Old Ones to the Outer Gods. From this, Tim learns of Nyarlathotep's goals to release the elder gods which would cause the very extinction of mankind.
With his mind broken, Nyarlathotep leaves him a hollow shell who spoke unintelligibly. The last track on the album reflects the deterioration of Tim's mind as he babbles nonsensically.
Freudian Excuse? Mitigating factors?
It's Nyarlathotep. As for characterization...it does give Nyarlathotep enough of a personality considering that it's a rather short song, but it establishes him as a sadistic abomination who very much earns his title of the "Crawling Chaos."
The only bad guy of the album not counting the Yith that possesses Tim. But this is where I'm hesitant on. The song attributes every evil and woe on Nyarlathotep's feet, but the debate is how much of this is actually onscreen. He does make it apparent that his goal is ultimately to release the Great Old Ones and Outer Gods and very clearly leaves a man a brainless mess. But that is where I am having hesitations with.