Season 4 of the popular series "Arrow" premieres on October 7, and one of the show's main mystery highlights is going to be how Oliver gets back to Starling City to fight Damien Darkh (Neal McDonough) who is described as someone with no sense of morality with the heart of darkness.

TV Line reported that Damieh Darkh had a brief appearance in Season 3 of Arrow when he visited Starling City but got outta Dodge before causing any commotion. The appearance was very brief indeed, not enough for viewers to get a glimpse of his shady character.

Early reports said Darhk will be a very different villain from the previous antagonists featured in the show, said CarterMatt. For one, McDonough's character will be wearing fancy costumes as he wreak havoc on Starling City and fights our heroes. Darhk is a very sinister and very complicated villain and is the closest thing so far to pure evil.

While most of the previous villains in Arrow have a specific ax to grind with Oliver Queen or have their own personal agenda, Darhk does not have any of those. Instead, he just wants to preserve his own self-interest, the report said.

Oliver Green will have his hands full in Arrow Season 4 as Darhk will be his greatest enemy and will play a major role in the show's next installment. Aside from Darhk, Oliver will be fighting anti-heroes, including Mr. Terrific and Anarky who will be played by, Echo Kellum and Alexander Calvert.

Rumors said Anarky will join forces with Darhk and they will form a formidable team against Oliver Queen. For his part, Mr. Terrific will be a gay character and expect his villainous portrayals to receive some minor tweaking.

Starling Has a New Mayor Who is Also a Member of Shadowspire

According to Variety, Falling Skies actor Ryan Robbins will play a recurring role as the new mayor of Starling City as Conklin, who is described as as a sadistic and cruel member of the Shadowspire.

Oliver will have flashback memories portraying Robbins as his adversary. Oliver will also have a major face-off against the leader of Shadowspire, Baron Blitzkrieg, played by British actor Jimmy Akingbola.

Another report by TVLine said that actress Jesi Ryan was tapped by Arrow producers to play as Jessica Danforth, a long-time friend of Queen's family and one who harbors political ambitions, including becoming Starling City's new mayor.