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David Opie

Updated 10/07/2016

With 75 years of comic book history to draw upon, CW's flagship show Arrow has successfully adapted a number of fan-favorite storylines with a unique Arrowverse spin that's resonated with audiences worldwide.

Few shows on TV have such an enduring legacy to uphold, which is why every episode is picked apart by viewers. We love to analyse each frame, and construct our own fan theories to explain exactly what's going on in obsessive detail. So check out our best Arrow season 5 theories below!

[Via CW]
[Via CW]

While not every fan theory turns out to be true, they're fascinating nonetheless, providing a deeper insight into the characters that we all know and love. With that in mind, take a look below at all of the fan theories currently circulating around Arrow Season 5 — and remember to come back regularly as we continue to update this list.

Who Is Prometheus?

[Via CW]
[Via CW]

Now that Prometheus has been unveiled, we're still none the wiser regarding his/her true identity, but the producers have offered a number of clues that suggest we could have seen this mysterious figure before.

Will Black Siren Become The Next Canary?

[Via CW]
[Via CW]

Laurel Lance's last words to Oliver were finally revealed:

"Make me a promise. Please don't let me be the last Canary. That way, a part of me will always be out there with you."

While there's a number of potential recruits that Oliver could train to become the next Black Canary, our money's on Earth 2's Laurel Lance, despite her villainous background.

How Does Supergirl Join The Arrowverse?

Stephen Amell released a set picture of himself suited up alongside Melissa Benoist, who plays Supergirl on CW's latest addition to their schedule. What we still don't know is whether Supergirl's world will merge with Arrow's, or whether the two will remain separate following the upcoming 4-way crossover.

How Will Deathstroke Return For The 100th Episode?

While filming the 100th episode, star Stephen Amell posted pictures of Deathstroke hanging out on set. The cheeky photo has sparked fan speculation about whether this will be a one-off appearance, or whether the mercenary will take center stage in an ongoing story arc.

How Does Robert Queen Return From The Dead?

After executive producer Marc Guggenheim revealed that actor Jamey Sheridan is set to return in Arrow's 100th episode, theories of how Robert Queen could cheat death began to circulate, ranging from time travel, to magic, to even Lazarus Pits. The question now is: could Moira Queen follow close behind?

More on this fan theory here: ‘Arrow’ Season 5: Robert Queen Cheats Death In 100th Episode With No Flashpoint In Sight

Will Harley Quinn Appear In Season 5 of Arrow?

[Via CW]
[Via CW]

Show runner Greg Berlanti explains how Warner Bros. asked his team to test out the Suicide Squad characters on TV before tackling the team on the big screen. Does this mean Harley Quinn could return in Season 5 of Arrow?

Will Flashpoint Affect Arrow?

[Via CW]
[Via CW]

Barry's actions in the Season 2 finale of The Flash will undoubtedly have some kind of impact on Star City, although it's unclear to what extent as of yet. Stephen Amell suggests that the changes will be minimal, confined mostly to Arrow's spinoff show. But there's a chance that any lost character could return as if nothing's happened, including Robert Queen — or even Laurel Lance herself.

3 Oliver Queens?

Amell has confirmed that he will play three different versions of Oliver Queen in Episode 97, 'Human Target', suggesting that this could be linked with Flashpoint and a potential merging of worlds.

Will Deathstroke Return To Wreak Vengeance In Arrow Season 5?

[Via CW]
[Via CW]

One particularly interesting Arrow Season 5 theory concerns DC's most prominent supernatural entity, The Spectre. People began to suspect that this iconic character could appear on Arrow after director James Bamford tweeted this cryptic message:

The Spirit of Vengeance is unlikely to appear though, as the show runners behind Arrow are determined to take the program back to its realist roots. However, there's plenty of characters from previous episodes of Arrow who could return to wreak vengeance against Oliver Queen, including one particular mercenary who's made headlines recently now it's been confirmed that he will star in the next Batman movie. There's nothing stopping Deathstroke from appearing both in the DCEU and on CW's network at the same time.

Green Lantern Will Appear In Season 5 Of Arrow — As A Villain

[Via CW]
[Via CW]

Fans have been clamouring to see Hal Jordan appear in the Arrowverse ever since the hero's hometown Coast City was first introduced as an Easter Egg in earlier seasons. This particular fan theory claims that not only will Green Lantern appear as a new character in Season 5, but it even goes so far as to suggest that he could start out as an antagonist, fighting Green Arrow under the control of a villain called The Puppeteer.

Remember to check back regularly as we continue to update this overview with the very best Arrow fan theories that the internet has to offer. In the meantime, check out this promo for Arrow Season 5 for clues on which direction the show will take next.

Which one of these Arrow Season 5 theories do you think could be true? Let us know in the comments!