Stephen Amell as ARROW or OLIVER - After a violent shipwreck, billionaire playboy Oliver Queen was missing and presumed dead for five years before being discovered alive on a remote island in the Pacific. When he returns home to Starling City, his devoted mother Moira, much-beloved sister Thea, and best friend Tommy welcome him home, but they sense Oliver has been changed by his ordeal on the island. While Oliver hides the truth about the man he's become, he desperately wants to make amends for the actions he took as the boy he was. Most particularly, he seeks reconciliation with his former girlfriend, Laurel Lance. As Oliver reconnects with those closest to him, he secretly creates the main character of Arrow - a vigilant to right the wrongs of his family, fight the ills of society, and restore Starling City to its former glory.
Katie Casidy as DINAH LAUREL LANCE - is a fictional character, the daughter of the original Black Canary from comic books publishing by DC Comics, who has appeared in modern stories and joined the Justice League. She first appeared in Justice League of America #219 (October 1983). This Black Canary is noted for her martial arts skills and her Canary Cry a high powered, sonic scream with the ability to shatter objects and incapacitate villains. As with the original Black Canary, this incarnation was created by writer Robert Kanigher and artist Carmine Infantino.
Willa Holland as THEA QUEEN - (it is insinuated) idolized Oliver as a child. They used to be close and, according to Oliver, she used to chase after him when she was younger; thus her given nickname, "Speedy." When her father and brother were both presumed dead, Thea felt alone — disconnected from the world. She fell into a life of drugs and partying to fill the void left by her father and brother. Oliver's reappearance has done little to fill that void, as he is hardly ever around to re-connect with his sister. After a string of "disappearances" and a murder charge, Thea herself is starting to wonder where it is exactly that Oliver "disappears" to.
Colin Donell as TOMMY MERLYN - Tommy Merlyn (born 1984) is a former billionaire "trustafarian", and the best friend of Oliver Queen.When Oliver returns to Starling City, Tommy believes the good times will roll again but is greatly mistaken as Oliver is a changed man. In Oliver's absence, he forms an on-again, off-again relationship with Oliver's ex-girlfriend Laurel Lance. He later goes to confront his father about why his trust fund was shut off. Malcolm replies by stating he cannot use his money unreasonably. In Year's End, Oliver is confronted by a very dangerous vigilante. This vigilante not only uses a new very distinctive arrow, but Oliver doesn't know this masked man is actually his best friend's father, Malcolm Merlyn. His mother died in 1992.
Paul Blackthorne as DETECTIVE QUENTIN LANCE - Detective Quentin Lance is a police detective, formerly a sergeant (having been demoted in "Year's End"), and is partners with Detective Lucas Hilton. He is the father of Laurel and the late Sara Lance. Lance is described as a "gruff, determined city detective" who believes true justice can only come from law and order.
Colin Salmon as WALTER STEELE - Walter Steele is the step-father of Oliver Queen and Thea Queen. He works at Queen Consolidated. Steele is described as "a commanding, upper-crust man".
Jessica De Gouw as HELENA BERTINELLI - secretly known as the vigilante the Huntress, is the daughter of a crime boss set on destroying her father's crime empire. She and Oliver become a couple at the end of the episode Muse of Fire. At the end of Vendetta, she was shot in the shoulder from a crossbow by her own father, but managed to survive with assistance from Oliver. She then left the city.
Colton Haynes as ROY HARPER - is a street-savvy teenager from the Glades. He is a love interest for Thea Queen. In the original Green Arrow comics, Roy Harper is Green Arrow's sidekick, and is the first to take on the codename Speedy, which happens to be Thea Queen's nickname in Arrow. He later left Green Arrow due to drug abuse and took on the codenames Red Arrow and Arsenal.
Sources: Arrow.wikia.com, Wikipedia.com, IMDB.com
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