The Flash is an American television series developed by Greg Berlanti, Andrew Kreisberg and Geoff Johns, airing on The CW. It is based on the DC Comics characterBarry Allen / Flash, a costumed superhero crime-fighter with the power to move at superhuman speeds. It is a spin-off from Arrow, existing in the same fictional universe. The series follows Allen, portrayed by Grant Gustin, a crime scene investigator who gains super-human speed, which he uses to fight criminals, including others who have also gained superhuman abilities.

Initially envisioned as a backdoor pilot, the positive reception Gustin received during two appearances as Barry on Arrow led to executives choosing to develop a full pilot to make use of a larger budget and help flesh out Barry's world in more detail. Colleen Atwood, costume designer for Arrow, was brought in to design the Flash's suit. The creative team wanted to make sure that the Flash would resemble his comic book counterpart, and not simply be a poor imitation. The series is primarily filmed inVancouver, British Columbia, Canada.

The Flash premiered in North America on October 7, 2014, where the pilot became the second-most watched premiere in the history of The CW, after The Vampire Diaries in 2009. It has been well received by critics and audiences, and won the People's Choice Award for "Favorite New TV Drama" in 2014. The series was renewed for a third season in March 2016,^[1] which premiered on October 4, 2016.^[2] The series, together with Arrow, has spun characters out to their own show, Legends of Tomorrow, which premiered on January 21, 2016.

• Grant Gustin as Barry Allen / Flash:

A Central City assistant police forensic investigator. Moments after an explosion at the S.T.A.R. Labs particle accelerator, Barry is struck by lightning in his laboratory and doused by chemicals affected by the accident. When he awakens from a nine-month coma, he has superhuman speed.^[8] In September 2013, Grant Gustin was cast in the titular role.^[8] Andy Mientus, who would eventually be cast as Hartley Rathaway, also auditioned for the role.^[9] Gustin began researching the character during the audition process, and reading as many comics as possible. Gustin primarily focused on The New 52 series of comics, because he knew it would be difficult to read everything and he felt the New 52 was the closest to the show's "look and feel".^[10] Gustin also portrays the Earth-2 version of the character, Barry Allen, who is not the Flash on this Earth.^[11]

• Candice Patton as Iris West:

She is the daughter of Detective West and Barry Allen's best friend and longtime crush.^[12] She works at Central City Picture News as a journalist.^[13] Patton also portrays the Earth-2 version of the character, Iris West-Allen, who is a detective at the Central City Police Department.^[11]

• Danielle Panabaker as Dr. Caitlin Snow:^[14]

Named after the civilian identity of the DC Comics character Killer Frost. A highly intelligent bioengineering expert, Caitlin believed her fiancé, Ronnie Raymond,^[14] was killed during the particle accelerator explosion at S.T.A.R. Labs,^[15] until he returned part way through first season. Ronnie and Caitlin get married in the first season finale, "Fast Enough".^[16] Panabaker also portrays the Earth-2 version of the character, Caitlin Snow / Killer Frost.^[11][17] In season 3 she is a metahuman now with the same powers as Killer Frost.

• Rick Cosnett as Eddie Thawne:

A recent transfer to the Central City Police Department, Eddie's past is a mystery and he harbored a dark secret.^[15] He is partner to Detective Joe West and Iris West's love interest. Cosnett left the series after the first season, following his character's sacrifice to wipe Eobard Thawne, his distant descendant, from history.^[16]

• Carlos Valdes as Cisco Ramon / Vibe: A mechanical engineering genius, Cisco is the youngest member of the team of scientists at S.T.A.R. Labs.^[18] Valdes also portrays the Earth-2 version of the character, Cisco Ramon / Reverb, a metahuman who works for Hunter Zolomon / Zoom.^[11]
• Tom Cavanagh as Dr. Harrison Wells:

The mind and money behind Central City's S.T.A.R. Labs Particle Accelerator, Wells becomes a pariah after the lab explodes.^[19] He serves as Barry’s mentor after he gains his powers, teaching him how to further develop his abilities. He is eventually exposed as the Reverse-Flash, Professor Eobard Thawne (portrayed by Matt Letscher), the Flash's time-travelling archenemy and a descendant of Eddie from the future, who murdered the real Harrison whilst transmuting his appearance as his own.^[20] Cavanagh later portrays the Earth-2 version of Harrison Wells, nicknamed Harry, in subsequent seasons. Harry travels to Earth-1 to seek help in rescuing his kidnapped daughter Jesse, and becomes a part of Barry's team.

• Jesse L. Martin as Joe West: A police detective who acts as a surrogate father to Barry, after his mother's death and father's imprisonment, and who is the father of Iris^[6][21] and Wally.^[22] Martin also portrays the Earth-2 version of the character, a musician.^[11]
• Keiynan Lonsdale as Wally West / Kid Flash:

The son of Joe and brother of Iris, born without their knowledge after his mother left Central City.^[22] The producers disliked the introduction of relatives of characters that were never previously mentioned, feeling it was "weird", and opted instead to introduce Wally as unknown even to his relatives. They also chose to make him Iris' brother, a departure from the comics where he was her nephew.^[22] Speaking on Lonsdale's casting, Kreisberg explained that “Just like when we met Grant [Gustin] for the first time, we instantly knew Keiynan embodied all the heart and courage of a hero."^[23] Wally becomes Kid Flash in season 3.[24]