Arrow may have a new villain by the end of the Season 3 finale.
TV Line is reporting the Arrow Season 3 finale will introduce a "major, formidable, fierce new foe" for Oliver Queen.
It's said the new villain's "reign of terror" will continue into Season 4.
According to the report, the mystery character is being referred to as "Damian Dark."
Note: Some outlets have mistakenly speculated it to be the son of Bruce Wayne, Damien Wayne, but I doubt a ten year old is going to be an opponent on the show for Arrow.
There is a character in the DC Comics with the name Damian Darkh, who is a 20-ish underworld figure who has access to advanced technology and often scraps with the Teen Titans.
Here is the description of the character from wiki:
Baby-faced Damien Darhk was a mysterious, elusive, and dangerous figure. He claimed to be a major player in America's underworld and certainly had some connection to the criminal organization H.I.V.E. He also seemed to have had access to unique high-tech equipment that has never been used by any known organization. Darhk was considered to be a major criminal by the C.I.A. and F.B.I.; however, their investigations revealed no hard evidence against him. He was a wi-fi fiend, staying in touch with associates by the very latest forms of mass communication. What particularly baffled investigators was his apparent youth; Damien seemed to be in his early twenties yet was already well-established and well-connected.