Holland is an original cast member of the series. Thea is Oliver’s (Stephen Amell) rebellious younger sister. She grew up pretty fast having to deal with both of her parents dying, finding out that Malcolm Merlyn (John Barrowman) is her biological father and all of the danger surrounding her brother’s secret identity. Thea joined Team Arrow under the red hood that Roy Harper (Colton Haynes) wore as Arsenal. She went by the code name Speedy.
Thea has suffered multiple injuries and death, returning to life in the Lazarus Pit by the League of Shadows. She departed in season 6, running away with Roy and Nyssa Al Ghul (Katrina Law) to find and destroy all of the Lazarus Pits. The last we heard about Thea, she had a falling out with Roy for bringing him back to life in one of the pits. Thea did not appear in the flash-forwards and no one mentioned her fate.
Holland is the latest name to reappear on the casting list for the final season. Barrowman returns as Malcolm Merlyn; Susanna Thompson as Moira Queen; Colin Donnell as Tommy Merlyn; Rila Fukushima as Tatsu Yamashiro/Katana; Josh Segarra as Adrian Chase/Prometheus; and Byron Mann as Yao Fei Gulong.
This is exciting news. Thea went through the biggest transformation from brooding teenager to superhero. Despite Oliver’s influence, Thea always made her choices on her own terms. She even left on her own terms, giving her an opportunity to return to the show, just in time for the finale. Does this mean she will be a part of the crossover as well? I think so.
The final season of Arrow premieres on Tuesday, October 15 on The CW.