who is the main villain in arrow season 4
List of Arrow characters In season four, Oliver is called from retirement to help Laurel and Thea stop a group known as "The Ghosts" led by Damien Darhk, leader of H.I.V.E. Oliver now goes by the name "Green Arrow", ostensibly a new vigilante following in the footsteps of the Arrow, who Star City (formerly Starling City) believes to have died. He plans to propose to Felicity and run for mayor. While on a mission with Barry Allen in Central City, Oliver meets Samantha Clayton's son, William, and ultimately learns that he is William's father. Samantha refuses to grant Oliver full access because of his playboy past and her ill feelings toward his mother. The revelations of his fatherhood complicates Oliver's relationship with Felicity and his duty as Green Arrow, and threatens to jeopardize his mayoral campaign. When a H.I.V.E. attack leaves Felicity permanently paraplegic, Oliver's fight with Darhk becomes a vendetta. Oliver also discovers that Thea is dying because the Pit's restorative effect on her is waning; Nyssa offers a cure in exchange for killing Malcolm. In a fight, Oliver cuts off Malcolm's left hand and gives the Demon's Head ring to Nyssa in exchange for the cure. Nyssa disbands the League of Assassins, causing Malcolm to seek vengeance against Oliver. As a result, Darhk kidnaps William, Oliver's relationship with Felicity becomes estranged, and Oliver is forced to resign from his mayoral campaign. After Darhk is successfully prosecuted, Malcolm, with help from Andy Diggle, aids Darhk's escape by restoring his magic, and fatally stabs Laurel with Oliver's arrow. Laurel dies of her injuries moments after admitting that she still loves Oliver, who is devastated. During his quest to stop Darhk, Oliver learns that the pure forces of light can counter Darhk's powers and that H.I.V.E. plans to rule a post-apocalyptic world. At the end of the season Oliver stops Darhk's plan to destroy the world and kills him. With the death of the previous mayor, Ruve Adams, Oliver becomes acting mayor of Star City. The season's flashbacks explore Oliver's training with A.R.G.U.S. and his infiltration of the Shadowspire organization on Lian Yu.
Sara Lance In season two, Sara returns to Starling City after six years' absence as "The Canary". After having saved Oliver twice, Felicity (Emily Bett Rickards) realizes that the female vigilante was actually protecting Laurel and not him. Setting a trap, he manages to capture and unmask her, and Sara reveals that she's alive to her father, SCPD Detective Quentin Lance. Some time later, Sara joins Team Arrow and revisits a brief relationship with Oliver. She aids him and his colleagues Diggle (David Ramsey) and Roy Harper (Colton Haynes) in taking down a drug-enhanced Slade Wilson, with help from the League of Assassins, which requires Sara to return to Nanda Parbat. In Arrow's third season, Sara is killed while on a rooftop by being shot three times with arrows on the chest. Some time later, it was revealed that Thea (Willa Holland) killed Sara after being drugged by her father Malcolm Merlyn (John Barrowman) as part of a plot to pit Oliver against Ra's al Ghul (Matt Nable). Meanwhile, Laurel takes up Sara's mantle to fight crime as the Black Canary. In season four, Laurel and Thea decide to resurrect her using League's mystical Lazarus Pit. The process is successful, but Sara is brought back to life without a soul, making her feral and dangerous. Oliver calls his old friend John Constantine (Matt Ryan) to assist them in restoring Sara's soul. Days later, Sara aids in rescuing Ray Palmer (Brandon Routh) from the hands of Damien Darhk (Neal McDonough), before leaving town to find herself.