Thea Dearden Queen is the 19 year-old daughter in the Queen Family. She is the birth daughter of Moira Queen and Malcolm Merlyn, the step-daughter of the late Robert Queen, and the late Rebecca Merlyn, the younger half-sister of Oliver Queen and the late Tommy Merlyn, a good friend of Margo, Morgan, Baker, and Sin, and the ex-girlfriend of Roy Harper. Thea was first seen as a reckless drug addict with temper issues but time spent with Laurel in the CNRI in community service made her more responsible. Later she met a street criminal, Roy Harper, who stole her purse, causing Thea to look for him, and then eventually causing her to fall in love with him and managed to persuade him to a life away from crime. She is now Roy's ex-lover and boss of Verdant.
After the death of her mother at the hands of Slade Wilson, Thea left Starling City with her biological father, Malcom, where she would be vigorously trained, until she later returned to Star City, living in a penthouse. She was later attacked in her penthouse by Ra's al Ghul in an attempt to blackmail her brother into joining the League of Assassins. She was last seen during the League of Assassins assault on the city wearing Roy's Arsenal suit.
Six months following the LoA’s assault on Star City, Thea has moved in with Laurel, unable to stay at her penthouse due to it triggering memories of the time Ra’s almost killed her. She is now a full time vigilante going under the name Speedy. It was soon discovered that using the Lazarus Pit to heal her from a coma had negative effects such as making her become overly aggressive when confronted; she attempted to burn Anarky to death during a fight with him.
Thea appears in 81 episodes of "Arrow" on the CW.