The Arrowverse is a shared fictional universe that is centered on television series airing on The CW, developed by Greg Berlanti, Marc Guggenheim, Andrew Kreisberg and Geoff Johns, based on characters appearing in publications by DC Comics. The shared universe, much like the DC Universe in comic books or the DC Extended Universe, was established by crossing over common plot elements, settings, cast, and characters.

The first television series was Arrow, based on the character Green Arrow, which debuted in October 2012. The universe was expanded with the series The Flash in October 2014, which is based on Barry Allen / Flash. In August 2015, Matt Ryan was confirmed to reprise his role as John Constantine from the short-lived Constantine series on Arrow, for a crossover episode. The universe expanded with the animated series Vixen which premiered on August 25, 2015 on CW Seed, and will expand again with the live-action team up series, Legends of Tomorrow, in January 2016.

On January 12, 2012, The CW was preparing a new series centered around the character Green Arrow, developed by Andrew Kreisberg, Greg Berlanti and Marc Guggenheim.^[1] A week later, the series, now known as Arrow, was ordered to pilot, which was directed by David Nutter, who also directed the pilot for Smallville, a series following Clark Kent on his journey to become Superman.^[2] At the end of the month, Stephen Amell was cast in the titular role of Oliver Queen.^[3] When developing the series, producer Marc Guggenheim expressed that the creative team wanted to "chart [their] own course, [their] own destiny", and avoid any direct connections to Smallville, which featured its own Green Arrow / Oliver Queen (Justin Hartley), opting to cast a new actor in the role of Oliver Queen.^[4]

In July 2013, it was announced that Berlanti and Kreisberg, along with Nutter and Geoff Johns, would be creating a television series based on The Flash, with an origin story for Barry Allen.^[5] The character, played by actor Grant Gustin, was set to appear in three episodes of season two of Arrow, with the final one acting as a backdoor pilot for the new series.^[6] However, it was announced in November 2013 that the backdoor pilot would not be happening, with a traditional pilot being made instead. The decision was made after the first two appearances of the character were well received by CW executives who saw the material. At the time, no decision was made as to whether the character would be featured in the third episode, which was set for the end of the second season and had not been written.^[7] It was also confirmed that the character's superhero persona would not be featured on Arrow as originally intended, but will be saved for the pilot episode of the new series.^[8] In January 2014, The Flash was officially ordered for a pilot episode.^[9] On January 11, 2015, The CW renewed The Flash for a second season.^[10] In October 2014, Geoff Johns explained DC's difference in approach regarding their films and television series to Marvel Studios and their cinematic universe, saying, "We look at it as the multiverse. We have our TV universe and our film universe, but they all co-exist. For us, creatively, it’s about allowing everyone to make the best possible product, to tell the best story, to do the best world. Everyone has a vision and you really want to let the visions shine through ... It’s just a different approach."^[11]

In January 2015, the CW announced that an animated web-series featuring the DC heroine Vixen would be debuting on CW Seed in late 2015. It is set in the universe of Arrow and The Flash.^[12] The character is expected to make a live-action appearance on The Flash and/or Arrow as well.^[13] Amell and Gustin will reprise their roles as Oliver Queen / Arrow and Barry Allen / Flash, respectively.^[14]

In February 2015, it was reported that a spin-off series, which is described as a superhero team-up show, was in discussion by The CW for a possible 2015-16 midseason release. Berlanti and Kreisberg would executive produce alongside Guggenheim and Sarah Schechter. The potential series would be headlined by several recurring characters from both Arrow and The Flash, including Ray Palmer, Leonard Snart / Captain Cold (Wentworth Miller), Dr. Martin Stein (Victor Garber) and Mick Rory / Heat Wave (Dominic Purcell). Caity Lotz is also mentioned to be among the main cast. There is potential for other Arrow/Flash characters to cross over to the new series.^[15][16] In March 2015, it was reported that Ciara Renée was cast as the superhero Hawkgirl and Arthur Darvill as the time traveler Rip Hunter.^[17][18] In May 2015, the CW officially confirmed the name of the spin-off as DC's Legends of Tomorrow,^[19] with filming expecting to begin in August 2015, for a January 2016 premiere.^[20]

In August 2015, CW president Mark Pedowitz stated, "There is no intention, at this point, to spin anything else off" to add to the universe.^[21] At the end of the month, in a video about the production of Vixen, Guggenheim referred to the universe the series share as the "Arrowverse".^[22]

In May 2015, Amell, revealed he had discussions with DC Entertainment to portray the character on Constantine, saying, "The reason that I was going to guest star on Constantine, at least the idea that we were throwing around was [Constantine's] an expert when it comes to the Lazarus Pit, which is now something that is a part of and will continue to be a part of Arrow." Amell stated that, even though Constantine was not renewed for a second season, a crossover "was and is still on the table".^[23] Additionally, Guggenheim revealed a desire to integrate Constantine into the universe that had been created with Arrow, saying, “A lot of the pieces are in place, except for that one final piece, which is what’s the fate of Constantine? That’s the tricky thing. But it comes up in the writers’ room constantly — we have a number of ideas, one idea that’s particularly exciting to me. We’re in a little bit of a wait-and-see mode”.^[24] In July 2015, additional Arrow showrunner Wendy Mericle added, "we really want to [include Constantine]. It's something we've been talking to DC about and it's just a question of some political things, but also the actor's schedule. We're trying to work it out, but we don't know 100 percent if it's going to happen. But we're really optimistic and we would love to have him," presumably talking about Constantine actor Matt Ryan.^[25] In August 2015, it was confirmed that Ryan would appear on Arrow in the fourth season per a "one-time-only-deal". Guggenheim said, "This is something the fans were clamoring for," praising DC for being so "magnanimous and generous in giving us this one-time dispensation." Due to Arrow and Constantine sharing the same studio, the producers of Arrow were also able to acquire Ryan's original outfits, with Guggenheim saying, "The trench coat, the tie, the shirt...the whole wardrobe is being taken out for storage and shipped up to Vancouver [where Arrow shoots]." John Badham, who was a director on Constantine, will direct the episode that Constantine appears.^[26] Mericle confirmed that this version of Constantine would be the same character that had appeared in Constantine.^[27] On filming the episode, Guggenheim stated it felt like the production team was "doing a Constantine/Arrow crossover, and it’s so exciting… We’re just really glad we got the chance to extend Matt Ryan’s run as Constantine by at least one more hour of television. I think you’ll see he fits very neatly into our universe. It never feels forced, it feels right."^[28]

The series follows Oliver Queen (Stephen Amell), billionaire playboy of Starling City, who spends five years shipwrecked on a mysterious island. Upon his return to Starling City, he is reunited with his mother, Moira Queen (Susanna Thompson), his sister, Thea Queen (Willa Holland), and his friend, Tommy Merlyn (Colin Donnell). The first season focuses on Oliver rekindling his relationships and spending his nights hunting down and sometimes killing wealthy criminals as a hooded vigilante. He uncovers a conspiracy to destroy "The Glades", a poorer section of the city that has become overridden with crime. John Diggle (David Ramsey) and Felicity Smoak (Emily Bett Rickards) assist Oliver in his crusade. Oliver also reconnects with ex-girlfriend, Laurel Lance (Katie Cassidy), who is still angry over his role in her sister's presumed death. The first season also features flashbacks to Oliver's time on the island, and how it changed him; this continues in subsequent seasons.

In season two, Oliver has vowed to stop crime without killing criminals, and comes under attack from Slade Wilson (Manu Bennett), a man from Oliver's time on the island who resurfaces with a vendetta against him. Oliver must also contend with outside forces attempting to take over Queen Consolidated, guilt from decisions he made in the past, and secrets harbored by his family and friends. Oliver grows to accept aspiring vigilante Roy Harper (Colton Haynes) as his protégé, and begins to receive assistance from Laurel's father, Officer Quentin Lance (Paul Blackthorne). Oliver also gains another ally; a mysterious woman in black, who is eventually revealed to be Laurel's sister, Sara Lance (Caity Lotz), who had survived her ordeal at sea years prior.

In season three, Arrow has become a public hero in Starling City following Slade Wilson's defeat. Queen Consolidated is sold to wealthy businessman, scientist, and aspiring hero Ray Palmer (Brandon Routh). Oliver struggles to bring his family back together, an old enemy returns, and Oliver becomes embroiled into a conflict with Ra's al Ghul (Matthew Nable). After a rocky start, Laurel sets out to follow in Sara's footsteps as the Black Canary. John Diggle struggles with his new role as a family man, as Oliver no longer wants him in the field after the birth of John's daughter, while Felicity Smoak begins a new career as Vice President of Palmer Technologies (formerly Queen Consolidated).

After witnessing his mother's supernatural murder and his father's wrongful conviction for the crime, Barry Allen is taken in by Detective Joe West and his family. Allen becomes a brilliant but socially awkward crime scene investigator for the Central City Police Department. His obsession with his tragic past causes him to become an outcast among his peers; he investigates cold cases, paranormal occurrences, and cutting-edge scientific advancements that may shed light on his mother's murder. No one believes his description of the crime—that a ball of lightning with the face of a man invaded their home that night—and Allen is fiercely driven to vindicate himself and to clear his father's name. Fourteen years after his mother's death, an advanced particle accelerator malfunctions during its public unveiling, bathing the city center with a previously unknown form of radiation and creating a severe thunderstorm. Allen is struck by lightning from the storm and doused with chemicals in his lab. Awakening after a nine-month coma, he discovers he has the ability to move at superhuman speeds. Dr. Harrison Wells, the disgraced designer of the failed particle accelerator, describes Barry's special nature as "metahuman"; Allen soon discovers that he is not the only one who was changed by the radiation. Allen vows to use his gifts to protect Central City from the escalating violence of metahuman criminals. He is aided by a few close friends and associates who guard his secrets.

After her parents were killed in Africa by local corruption, Mari McCabe inherits her family's Tantu Totem, gaining the powers of animals, using them to fight as Vixen to stop threats like those that claimed her family.^[30]

On November 6, 2013, a six-episode series of shorts, titled Blood Rush, premiered alongside the broadcast of Arrow, as well as online. The series, which was presented by Bose, and features product placement for Bose products, was shot on location in Vancouver, similarly to the main show. The miniseries features Emily Bett Rickards, Colton Haynes and Paul Blackthorne reprising their roles of Felicity Smoak, Roy Harper and Quentin Lance, respectively.^[31]

Beyond brief mentions throughout various episodes, there have been multiple episodes that have featured characters crossing over to other series as well as official crossover episodes.

^ 1. Emily Bett Rickards was promoted to series regular of Arrow in season 2, after portraying her character in a recurring capacity for season 1.^[54]

^ 2. While Legends of Tomorrow has not be confirmed to have an official crossover episode with Arrow and The Flash, a number of characters who will star and recur in the series will be set up in the Arrow and The Flash crossover.^[53][56]
^ 3. This episode features Matt Ryan's reprisal of John Constantine from Constantine.

In April 2015, to celebrate the season three finale of Arrow and season one finale of The Flash, The CW released a short promo titled "Superhero Fight Club".^[57] The short features characters from Arrow and The Flash battling each other in a hero vs. villain showdown. Characters include Arrow, Flash, Arsenal, Black Canary, Captain Cold, Heat Wave, Firestorm, Ra’s al Ghul, and the Reverse-Flash in a cage match fight.^[58]

Rip Hunter travels back in time to the present day where he brings together a team of heroes and villains in an attempt to prevent Vandal Savage from destroying the world and time itself.^[68][69]

By September 2014, Warner Bros. Television was looking to create a television series centered around Supergirl. Executive producers for the series include Greg Berlanti (also a creator/producer for Arrow and The Flash), Ali Adler, who are both writing the script, and Berlanti Productions' Sarah Schechter. DC Comics' Geoff Johns is also expected to be part of the project.^[70] Berlanti confirmed the show shortly after, and stated it was in development and had yet to be pitched to networks.^[71] On September 19, it was announced that CBS had landed Supergirl with a series commitment,^[72] and is expected to premiere in 2015 of the 2015–16 television season.^[73]

In November 2014, Berlanti expressed interest in Supergirl existing in the same universe as his other series Arrow and The Flash,^[74] and in January 2015, The CW president Mark Pedowitz revealed that he was also open to a crossover between the series and networks (due to Berlanti executive producing all three and The CW co-owned by CBS). However, Tassler stated that month that, "those two shows are on a different network. So I think we'll keep Supergirl to ourselves for awhile."^[75] In August 2015, Tassler revealed that while there were no plans at the time to do story crossovers, the three series would have crossover promotions.^[76]

At San Diego Comic-Con 2014, actor David Ramsey revealed that there had been talk of a spin-off that would focus on Arrow's version of the Suicide Squad.^[77] However, Arrow co-producer and comic book writer Keto Shimizu stated in January 2015 that with the Suicide Squad feature film in development, "it doesn't seem like it’s a possibility."^[78]