Production on "Arrow" Season 5 is already underway, and -- considering the big team shakeup in Season 4 -- a lot of change is coming to Star City. From new vigilantes to new villains to new costumes, "Arrow" promises viewers something of an overhaul when Season 5 rolls around, and CBR has broken down everything we know so far to prepare you for Oliver Queen's bold new world.

11 "Vicious, Violent" Season Opener



Production on "Arrow" Season 5 has already begun, and Amell took to Facebook to promise that the show will be bloodier than ever. According to the "Teenage Mutant Ninja Turtles: Out of the Shadows" star, the premiere episode -- titled "Legacy" -- "has the opportunity for us to have the most vicious, violent one-shot in the history of network television." And by "one-shot," Amell means a continuous take fight scene like "Daredevil's" infamous hallway and stairwell scenes, or Daisy's one-take battle in the "Agents of S.H.I.E.L.D." episode "Spacetime."

"If [the premiere] is any indication, 'Arrow' is going to be f---ing mean this year," he added, "and that's really exciting." Amell later clarified, he doesn't mean "evil" -- just plain mean.

10 New Vigilantes



In the "Arrow" Season 4 finale, both John Diggle and Thea Queen left Star City seeking respite. Considering this and the death of Laurel Lance, Team Arrow has some pretty big gaps to fill, but there's no need to worry -- three new vigilantes will rise up to take their place.

Meet Wild Dog. The character -- played by "Mr. Robot" star Rick Gonzalez -- is described as "...a new vigilante in Star City whose reckless and cocksure nature prompts Green Arrow to take him under his wing." First appearing in the comics in his own series in 1987 by Max Allan Collins and Terry Beatty, the character was an auto mechanic named Jack Wheeler who took on the guise of Wild Dog to fight urban crime. He started out primarily fighting American terrorists led by the "Committee for Social Change," and stood apart from his fellow heroes by using deadly force to take down his targets.

And then there's Adrian Chase, "Star City's new district attorney and an ally of Mayor Oliver Queen, who aims to clean up the streets through the legal system." "Chicago P.D." star Josh Segarra will play Chase, who -- in the comics -- also masquerades as the Vigilante. He debuted in 1983's "New Teen Titans Annual #2," where he took up the Vigilante mantle to seek justice for his family's murder by mobsters. He is also connected to Deathstroke, who appeared as the primary antagonist of "Arrow" Season 2. It is unclear if Chase will also be Vigilante when he arrives on "Arrow" Season 5, or if he will develop into this role.

Madison McLaughlin's Evelyn Sharp will also make her way back to "Arrow" for Season 5, but this time as the vigilante known as Artemis. McLaughlin appeared as Sharp in the Season 4 episode "Canary Cry," where she impersonated Black Canary shortly after Laurel's death; in Season 5, however, she'll appear in multiple episodes, starting with the second episode of the season. In the comics, Artemis -- the daughter of Tigress and Sportsmaster -- was an active member of the Injustice Society. However, the animated series "Young Justice" turned her around, and she became Green Arrow's apprentice following Roy Harper's exit.

Dig, Thea and Laurel won't be the only ones getting replaced. Tyler Ritter's Detective Malone will also stand in for Captain Lance on the Star City Police Department.

9 New Villain



Star City's new villain will rise alongside this influx of vigilantes. Chad Coleman's Tobias Church is "an imposing gangster looking to unite the various criminal enterprises in Star City under his own singular command" and an original character not pulled from the DC comics. The character has been compared to Idris Elba's "Wire" character Stringer Bell, with the physicality of "Game of Thrones" alum and current "Aquaman" star Jason Momoa. Church will set out to fill the void left by Damien Darhk and H.I.V.E. in the aftermath of season four.

"I've heard that our big bad, our villain, is something that you can really only do once you're in the fifth, sixth or seventh season of a TV show," Amell said of the character. "As far as I know, they don't have superpowers. I'll tell you that."

8 A Little Bit of Coast City



Oliver Queen went for a visit in Hal Jordan's hometown Coast City in Season 4, but a little bit of Coast City will come see him in Season 5. "The Tomorrow People's" Carly Pope has been cast as Coast City reporter Susan Williams, who -- in the comics -- is the Green Lantern's sister-in-law. Williams will come to Star City "looking to make a name for herself" by going after Oliver Queen for a "big story."

7 Diggle Will Get a Costume Upgrade



Last summer, Diggle got his first ever Team Arrow costume -- and it came under heavy fire from fans and skeptics alike. It seems as though the executive producers heard fans' cries, though, because Dig will get an all-new mask come Season 5.

"Season 5, you will see a Cisco-created new mask for Diggle," Ramsey told audiences at Heroes And Villains Fan Fest 2016. He had teased the upcoming costume change in January, though he didn't reveal when Diggle would get this update at the time: "Central City will be working on an upgrade to Diggle's helmet. That is yet to come, and we will be seeing some of that come out of Central City. As the first iteration came out of Central City, we will see an upgrade also come out. But in terms of Central City's help with technology to help us combat the magic, that has yet to be seen."

Though Diggle quit Team Arrow and reenlisted in the military at the end of "Arrow" Season 4, Ramsey's latest comment makes it seem as though he won't be away from Star City for too long.

6 Curtis Will Become Even More Terrific



Executive producer Wendy Mericle also weighed in on Curtis Holt's role in Season 5, and -- with some careful wording -- revealed that he will become a little more Terrific this year.

"Essentially, if [Felicity] is software, he's hardware," Mericle said. "As he evolves into becoming Mr. Terrific in Season 5, one of the things we're really exploring is differentiating them by having Curtis be more like Cisco on 'The Flash.' We want him to be a bit more hands-on, a little more about building physical tech."

In the comics, Mr. Terrific's secret identity is Michael Holt, an extremely intelligent, Olympic-level athlete. Mr. Terrific is also member of the Justice Society of America, who joined after the death of his wife and unborn child, though it seems the show will craft a new origin to go with the new name. Obviously, "Arrow" has deviated from this origin story and will likely continue to develop the character in a different direction.

The comparison to "The Flash's" Cisco Ramon could also indicate that Curtis' transformation into Mr. Terrific may be a slow burn. Two seasons into "The Flash," Cisco has yet to become a costumed vigilante himself, though he continues to explore his powers; Curtis will likely walk a similar path in "Arrow" Season 5.

5 Black Canary -- Never Forgotten, and a Long-Awaited Return



"Arrow" Season 5 will be honoring the brief, heroic life of Black Canary after her demise in Season 4 of the hit CW series. Writer-producer Marc Guggenheim unveiled a piece of production art on Twitter, indicating that Star City will be memorializing Laurel Lance in the form of a statue at some point in the next season.

Arrow Season 5 production art glimpse... pic.twitter.com/HVTWDWjtp0- Marc Guggenheim (@mguggenheim) June 22, 2016

4 A Long-Absent Character Will Return



Amell revealed that "Arrow" season five will also feature the return of a mystery character -- "someone that we haven't seen in two full seasons." That is to say, someone we haven't seen since the first two seasons of the series.

While he didn't provide any other clues about the identity of this mystery character, CBR took a stab at speculating just who might return for Season 5 by running down a few characters we haven't seen on the show in a while.

3 Olicity No More?



At Heroes and Villains Fan Fest, Amell addressed the future of Olicity.

"I was chatting with a couple of fans earlier and they were saying there hasn't been a lot of positivity and reassuring notions when it comes to Oliver and Felicity's relationship," he said. "I think that it's important to remember that relationships on the show don't have to be only defined by romance. Oliver and Felicity could have a wonderful, fulfilling, dynamic relationship and not be together, right?"

When the comment was met with boos from the audience, he added, "That wasn't a question, okay. That's how the world works! So we will see where they are this year... I hope that they're both in a happy positive place. Whether that means they're together or not remains to be seen."

2 Stardust Rematch



Cody Rhodes, the former WWE star known as Stardust whose feud with Stephen Amell culminated in tag-team match at SummerSlam, will guest star on the upcoming season of "Arrow." He will appear in the third episode of Season 5.

"You can probably expect Stephen [Amell] and I to get into another fight," Rhodes said, hinting that the duo's in-ring rivalry will spill onto Star City's streets.

1 Expected 4-Night DCTV Crossover



With "Supergirl" joining "Arrow," "The Flash" and "DC's Legends of Tomorrow" on the network next season -- all shows under the purview of executive producer Greg Berlanti -- the time is ripe for a massive crossover of all four shows, and Amell predicts that the superhero team-up will air across one single week as a four-night extravaganza.

"I think what we'll end up seeing is one giant four-night crossover. This is kind of an unprecedented moment in terms of the history of network television. To have four shows [with the] same showrunner," he explained, referring to Berlanti.

However, he draws the line at a musical crossover: "No. I'm out! I'm the first one. I get to draw the line, and I draw the line at musical."

Starring Stephen Amell, Emily Bett-Rickards and David Ramsey, "Arrow" will return to The CW on Wednesday, October 5 at 8 pm EST.