During a recent Facebook live session, "Arrow" star Stephen Amell revealed a few key details about the show's Season 5 premiere. For one, it presents the cast and crew with "the opportunity for us to have the most vicious, violent one-shot in the history of network television." Beyond that, the series will, according to Amell, "be f---ing mean this year." Perhaps most intriguingly of all, though, is the promise that Season 5 will feature the return of "someone we haven't seen in two full seasons."

Amell Says "Arrow" Premiere Will Have "Most Vicious, Violent" Fight In Network TV History

But who could this mystery character be? Well, as it turns out, there are quite a few potential candidates. CBR has narrowed that list down to the most likely, with a focus on living characters per Amell's comments, who last appeared in Season 1 or 2.

Deathstroke



First, we'll address the orange-and-black elephant in the room. Deathstroke was the big bad of Season 2, but he's been locked away on Lian Yu in A.R.G.U.S. custody ever since. Yes, Slade Wilson had a moment to confront Oliver and Thea in the Season 3 episode "The Return," but that doesn't totally disqualify Deathstroke from being in the running for this mysterious returning character.

Hear us out. Deathstroke could appear in "Arrow" Season 5 even if Wilson doesn't, because "Deathstroke" has become a mantle, not a person. For example, Wilson's son Grant assumed the name and the costume in the "Legends of Tomorrow" episode "Star City 2046," which flashed forward to a dire future where he terrorized Star City. Obviously, if Deathstroke returns, it won't be Grant behind the mask; he's far too young to fill his father's shoes in the present Star City. But what if a new Deathstroke was inspired by the chaos Deathstroke brought to Star City in Season 2? Isabel Rochev certainly was before her death, when she assumed the Ravager mantle. Bringing in a new Deathstroke would be an attention-grabbing move on the show's part, and could introduce a story arc about the mystery of the man (or woman) behind the mask.

Huntress



Huntress from Arrow series

In the absence of Spartan, Speedy and Black Canary, "Arrow" has been casting new vigilantes left and right. Artemis, Wild Dog and Vigilante are just three new heroes who will rise in Star City this fall. Of course, Helena Bertinelli -- aka Huntress -- is more of an anti-hero than a hero. She did try to kill her mob boss father, after all, and was subsequently sent to prison for murder -- and that's the last we saw of her. In the two years since, she could have been released, or maybe even escaped. Either way, if she returns, perhaps it won't be with a vengeance this time, but with clarity and a desire to make up for the sins of her past. After all, she regretted the actions that led her to prison, so she could certainly turn around and try to clean up the mess left in Damien Darkh's wake. If Oliver can do it as Green Arrow, she can do it as Huntress.

Sin



On that same note, Sin would be perfect for a Star City comeback. She more or less disappeared after Season 2, despite her recurring role and strong connections to then-Black Canary Sara Lance and Roy Harper. (She did appear briefly in the Season 3 episode "Uprising," but only to point out to Quentin Lance that the Black Canary they saw was not Sara.) With the impending flood of new vigilantes, Sin could easily assume a mantle of her own; barring that, she could also take up the Black Canary name, as Laurel did in the wake of Sara's death. Either way, Sin is an established character who would fit right back into Oliver's world, especially now that the Lances are gone.

Of course, Bex Taylor-Klaus -- who played Sin -- is currently a main character on MTV's "Scream," which may significantly decrease her chances of reprising her role. However, there's no reason she couldn't return for a one-off appearance in the Season 5 premiere, or for a short aarc over a few episodes.

China White



Chien Na Wei, who is otherwise known as China White, was a main "Arrow" villain until she went to prison in Season 2. Since then, she and the Chinese Triad haven't resurfaced at all. An organization as large as the Triad doesn't simply disappear because one of its leaders is locked away; perhaps they've been there all along, lurking just behind-the-scenes. Either way, they're long overdue for a comeback. What's more, if China White were to escape prison, her renewed presence on the streets of Star City would serve as a nice intersection of Oliver's new and past lives. He would have to deal with his old nemesis and her organized crime ring in his new role as mayor, even as he continues to try and clean up the streets of Star City as the Green Arrow.

Count Vertigo (Werner Zytle)



Here comes another mayoral problem for Oliver to deal with -- drugs, the tool of Count Vertigo's trade. Like China White, Count Vertigo's return would provide a neat contrast between Oliver's public and vigilante personas. Vertigo did appear briefly in the Season 3 episode "Canaries," but didn't stick around very long, so we're throwing his name into our mix of potential candidates. An expanded role in Season 5 would provide some nice conflict for Oliver's new position, as Oliver attempts to clean up the streets of Star City using conventional methods in addition to his more brutal ones.

Cyrus Gold



Alright, so Cyrus Gold is a bit of a cheat sine he technically died in the Season 2 episode "Three Ghosts." However, we can't count him all the way out, because his similarities to DC Comics baddie Solomon Grundy are just too strong; Diggle even recited the Solomon Grundy nursery rhyme in connection to the character, which suggests death may not stick to him too readily. A Mirakuru-infected beast, Gold would pose a formidable threat to Star City if he were to resurface. Plus, his death scene -- which entailed a spray of chemicals and a roof collapse -- wasn't entirely convincing. Don't believe us? See it for yourself in the clip below:

Anatoly Knyazev



Anatoly is a bit of a deep dive, but hear us out. Executive producer Wendy Mericle recently revealed that Season 5's flashbacks will show "how Oliver got that Bratva tattoo and how he learned to speak Russian." Over the course of Season 2's flashbacks, Oliver made a deep connection to Anatoly, a prisoner on Lian Yu who Oliver saved from Anthony Ivo; in present day Season 2, he also helped break Lyla Michaels, Diggle and Floyd Lawton out of a gulag. Perhaps Season 5's flashbacks will show Oliver's relationship with Anatoly in more depth, and -- seeing as the flashbacks often parallel the present -- maybe Anatoly will even drop by Star City to visit Oliver in office.

Starring Stephen Amell, Emily Bett Rickards and David Ramsey, "Arrow" will return to The CW this fall on Wednesdays at 8 pm EST.