Season 4 (The Flash)

The Flash was renewed for a fourth season by The CW on January 8, 2017. It premiered on October 10, 2017.

Main cast

 * Grant Gustin as Barry Allen/The Flash
 * Candice Patton as Iris West
 * Danielle Panabaker as Caitlin Snow/Killer Frost
 * Carlos Valdes as Cisco Ramon/Vibe
 * Keiynan Lonsdale as Wally West/Kid Flash
 * Neil Sandilands as Clifford DeVoe/The Thinker
 * Tom Cavanagh as Dr. Harrison "Harry" Wells and TBA
 * Jesse L. Martin as Detective Joe West

Recurring cast

 * Hartley Sawyer as Ralph Dibny/Elongated Man
 * Kim Engelbrecht as "The Mechanic"
 * Danny Trejo as "Breacher"
 * Jessica Camacho as Gypsy
 * Anne Dudek as Tracy Brand
 * Katee Sackhoff as Amunet Black/Blacksmith

Synopsis
"Running up against an evil time remnant version of yourself is something no one should ever have to do, but that’s exactly what faced Barry Allen (aka The Flash) as he fought to save the life of fiancée Iris West from the God of Speed known as Savitar."

"Barry’s victory was short-lived, however, as an unbalanced Speed Force began to wreak havoc on Central City, forcing Barry to sacrifice himself for the greater good."

"With The Fastest Man Alive now trapped inside an extra-dimensional energy, and unknown dangers lurking in the shadows, it will be up to Team Flash to free Barry from his own personal Hell."

Confirmed plot points

 * The main villain this season will not be a speedster.
 * The main villain will be DeVoe, who was mentioned in the previous season by Abra Kadabra and Savitar.
 * There will be a four-way crossover with Supergirl, DC's Legends of Tomorrow and Arrow.
 * The crossover will take place over two-nights and will consist of 2 "two-hour miniseries". The first "two-hour miniseries" will consist of Supergirl and Arrow while the second one will consist of The Flash and DC’s Legends of Tomorrow.
 * The crossover will have high emotional stakes and emotional payoffs with romance in the air.
 * The title of the crossover is Crisis on Earth-X.
 * The live action debut of The Ray will happen in the crossover.
 * Wally will wear Barry's suit this season.
 * Shawna Baez/Peek-a-Boo will return this season.
 * A superhero from the DC Comics called Elongated Man will make a recurring appearance throughout this season.
 * A villain named The Mechanic will be a recurring character this season who builds devices for DeVoe.
 * Gypsy's father will be introduced.
 * Harrison "Harry" Wells will be a part of the season but another version of Harrison Wells might show up.
 * Tom will direct at least one episode this season.
 * Barry will get a new suit that resembles the 2024 suit he saw when he met his future-self in 2024.
 * Tracy Brand will return at some point but she won’t necessarily be a full-fledged member of Team Flash.
 * A villian named Hazard will appear in the third episode.
 * Felicity Smoak will appear in the fifth episode.
 * Amunet Black/Blacksmith will make her first appearance in the same episode.

Confirmed new characters

 * Clifford DeVoe/The Thinker: After being struck with dark matter from the particle accelerator explosion, Clifford DeVoe became a meta-human with a mega-mind. A Stephen Hawking-esque genius who's devised an intricate plan to fix all that he deems wrong with humanity. "The Thinker" will embark upon a season long battle with the Flash that pins the "fastest man alive" against the "fastest mind alive".
 * Ralph Dibny/Elongated Man: Ralph has the ability to stretch his body to super-human lengths and sizes... however, while resculpting his old body is easy to do, Dibny finds losing the old misguided sense of truth and slobbery, even after joining the team at S.T.A.R. Labs, is a far more difficult task to accomplish.
 * The Mechanic: An extremely intelligent engineer who will design devices for Clifford DeVoe. Basically, DeVoe's right hand. She’ll support Devoe no matter the consequences.
 * Breacher: Earth-19 bounty hunter Gypsy's imposing father. Also a feared bounty hunter, he seeks to prevent any inter-dimensional traveler from threatening life on his planet - especially his daughter's.
 * Rebecca Sharpe/Hazard: Perpetually down-on her luck and is convinced her life is cursed — until a freak accident changes everything. With the universe on her side, she poses a threat to both Team Flash and Central City.
 * Amunet Black/Blacksmith: A steely and badass boss of an underground black market for supervillains. Amunet uses every means possible, including the long list of metahumans under her thumb, to ensure her illicit enterprise thrives.