The reunion of actors in the fifth season finale of Arrow continues to grow. The current season of Arrow has been a big one. Not only has the entire season featured flashbacks to Oliver's final year away after being shipwrecked, but smack in the middle of the four series Arrowverse crossover event came the series' 100th episode. Because most of the episode took place inside a fantasy world where Ollie and his father never boarded The Queen's Gambit, many characters who died during the series were alive and well in the story; Robert and Moira Queen, Laurel Lance, and an unseen Tommy Merlyn were all living the lives they never got to live in the real world.
And an even larger reunion has been promised for the season finale 'Lian Yu' this coming Wednesday. Slade Wilson, Captain Boomerang, Nyssa al Ghul, and Malcolm Merlyn are teaming up with Oliver to save his friends and family from Adrian Chase - who is helped by his own team including Talia al Ghul, Evelyn Sharp, and Black Siren. Photos have also revealed the return of Samantha - the mother of Ollie's child William. and they are not the only ones coming back.
Stephen Amell revealed in a tweet that someone who has not been seen in any of the trailers - he wouldn't say who specifically - is also returning.
My favorite cameo in the #Arrow Season Finale is not featured in any of the previews. Love this person so much for coming back.
— Stephen Amell (@StephenAmell) May 20, 2017
There are many possibilities for who could be coming back. Susanna Thompson as Moira Queen is certainly among the more likely; since the final flashback is supposed to come full circle to Ollie's "rescue" from Lian Yu five years ago, it's possible that his reunion with his mother could play a part in that story's closure. It also might be meaningful for Moira and Slade to appear in the same episode - since he killed her back in Season 2.
Other popular theories include two of Oliver's best friends - Tommy Merlyn and Roy Harper. Tommy died at the end of Season 1, but still showed up several more times in flashbacks, and once as a hallucination. Actor Colin Donnell didn't film any footage for the 100th episode because he was busy with his role on Chicago Med, so it would be a nice compromise for him to appear here. Tommy is another character who might appear in the flashback. Meanwhile, Roy Harper is alive and in hiding last we knew, but he might be yet another of Chase's hostages - after all, if Chase found William, he could probably find Roy too.
Of course, the returning person might not have been someone who was around as much as Roy, Tommy, or Moira. It could be an ally or enemy who was only seen in a few episodes - much like Captain Boomerang and Talia al Ghul. And since most of the returning characters have been adversaries and not friends, the likelihood that whoever Amell is talking about played a bad guy instead of a good guy is all too probable.
The fifth season finale of Arrow, 'Lian Yu', will air on The CW Wednesday, May 24 at 8 pm.
Source: Stephen Amell