Arrow's on-again and off-again relationship with Nyssa al Ghul is back on, as actress Katrina Law is returning for a season 6 episode. Since first appearing season 2, Law has been a pretty frequent guest star on Arrow. Nyssa has appeared in multiple episodes of every season of Arrow, following her introduction. The last of them came in the end of season 5, which left her fate up in the air.
Nyssa was a part of the group of heroes (and one-time villains) that Oliver took to Lian Yu to take down Prometheus AKA Adrian Chase. When the island blew up, as part of Chase's master plan, it was unclear if Nyssa survived. The season 6 premiere didn't clear things up much either. While Slade Wilson mentioned that Ra's al Ghul's daughter was somewhere on the island when Oliver returned, that could have easily referred to Nyssa or her elder sibling Talia. Now, however, it seems clear that Slade was talking about Nyssa. Arrow is making the most of Nyssa's survival as her return heralds an "unforgettable" episode.
Related: Why The CW Needs To Cancel Arrow
Variety reports that Law will be back for just a single episode, until further notice. The wait for Nyssa's return won't be very long either, as she set to make her return in episode 16 of season 6, which is titled "The Thanatos Guild". Arrow's co-showrunners Wendy Mericle and Marc Guggenheim issued the following joint statement about the news:
In an unforgettable episode that will change Arrow forever, Katrina Law returns as the Daughter of the Demon, Nyssa Al Ghul. Nyssa comes to Star City to warn of an impending danger that will threaten everything we know and love.
Guggenheim and Mericle didn't reveal any more plot details about Nyssa's return. However, what has been provided is more than enough to go on for hardcore Arrow and comic fans. The name of the episode of Nyssa's return really stands out. Though the Thanatos Guild appears to be an Arrow creation, there is a rather prominent character in DC AND Marvel Comics with that name. The DC version of Thanatos is, in fact, an "evil twin" of Aquaman. It's true that the arrival of Aquaman or an Aquman adjacent character would be surprising and game-changing move for Arrow (though the character has been referenced in the Arrowverse before).
However it's more likely that Thanatos will be closer to the Marvel version of the character, who is a Greek god and the personification of death. However, this isn't an original character, as Thanatos is a Greek God of ancient mythology who is also a personification of Death. With this in mind, it's reasonable to assume that Nyssa will return to Arrow to warn the show's heroes about the episode's eponuymous guild, as well as the presumed death worshippers who fill its ranks. Perhaps the Thanatos Guild will even be the replacement for the League of Assassins, which was dissolved during Arrow season 4.
Interestingly, Nyssa isn't the only major Arrow character to return for season 6. Deathstroke previously returned for his apparent "farwell arc" earlier in season 6. The season will also welcome back Colton Hayne's Roy Harper for a multi-episode story - a tale that will begin immediately before Nyssa's grand re-appearance. Since Roy's return is also set to have "long-lasting" consequences, it's not much of a stretch to think Nyssa and Roy's arrival will be connected in some way.
Fans will just have to wait to see how it all plays out. At the very least, Arrow season 6 is seems to be aiming to please long-time fans of the series.
Arrow season 6 continues with "We Fall" on Thursday, January 25 at 9/8c on The CW.