What's Past Is Prologue

"If I do this, I'm going back to some crazy times. Savitar, Zoom, Thawne, speedsters... Who you've all outsmarted and defeated."

- Barry Allen and Iris West-Allen

Synopsis
In the 100th episode, Barry and Team Flash come up with a plan to stop Cicada. However, the plan calls for Barry and Nora to travel back in time to gather some key necessities. However, Barry hesitates, concerned about his daughter seeing certain parts of his life. Meanwhile, Sherloque takes his concerns about Nora to Iris, and Caitlin turns up a key asset in the fight against Cicada.

Protagonists

 * Team Flash
 * The Flash (Barry Allen)
 * Iris West-Allen
 * Vibe (Cisco Ramon)
 * Killer Frost (Caitlin Snow)
 * Elongated Man (Ralph Dibny)
 * XS (Nora West-Allen)
 * Harrison Sherloque Wells
 * The Flash (Barry Allen) (Earth-90)

Antagonists

 * Clifford DeVoe
 * Harrison Wells (Eobard Thawne)
 * Zoom (Hunter Zolomon)
 * The Monitor (Mar Novu)
 * Cicada (Orlin Dwyer)
 * Savitar
 * Time Wraith

Other Characters

 * Gideon
 * Grace Gibbons
 * Grace Gibbons' Father
 * Henry Allen
 * Joe West
 * Nora Allen
 * Grace Gibbons' Mother
 * Ronnie Raymond

Before March 18, 2000

 * God
 * Henry Allen
 * Nora Allen

December 11, 2013

 * Barry Allen
 * Clifford DeVoe
 * Thinker (Clifford DeVoe)
 * Clyde Mardon
 * Gideon
 * Iris West
 * Mark Mardon
 * Marlize DeVoe
 * Martin Stein
 * S.T.A.R. Labs
 * Caitlin Snow
 * Cisco Ramon
 * Harrison Wells (Eobard Thawne)
 * Grodd
 * Hartley Rathaway
 * Ronnie Raymond
 * Vanessa Ambres

January 27, 2015

 * Barry Allen (2016)
 * Danica Williams
 * Dawn West-Allen
 * Dawn's Sibling
 * Harrison Wells (Eobard Thawne)
 * Jesse Chambers Wells
 * Libby Lawrence
 * Savitar

April 29, 2016

 * Jesse Wells
 * Team Flash
 * Caitlin Snow
 * Cisco Ramon
 * Harry Wells
 * Iris West
 * Joe West
 * Wally West

May 23, 2017

 * Savitar (Barry Allen)
 * Team Flash
 * The Flash (Barry Allen)
 * Killer Frost (Caitlin Snow)
 * Vibe (Cisco Ramon)
 * Iris West
 * The Flash (Jay Garrick)
 * Kid Flash (Wally West)

Speed Force Visions

 * Thinker (Clifford DeVoe)
 * Dominators
 * Edwin Gauss
 * Reverse-Flash (Eobard Thawne)
 * Grodd
 * Pied Piper (Hartley Rathaway)
 * Hunter Zolomon
 * Marlize DeVoe
 * King Shark (Shay Lamden)
 * Nora Allen (Speed Force)
 * Team Flash
 * The Flash (Barry Allen)
 * Killer Frost (Caitlin Snow)
 * Vibe (Cisco Ramon)
 * Gypsy (Cynthia)
 * Henry Allen
 * The Flash (Iris West-Allen)
 * The Flash (Jay Garrick)

Elseworlds Cold Open

 * Earth-90 Vigilante Group
 * The Flash (Barry Allen)
 * Captain Cold
 * Firestorm
 * Hawkgirl
 * Hawkman
 * Huntress
 * Jesse Quick
 * Obsidian
 * Green Arrow
 * Stargirl
 * The Ray

Teams and Organizations

 * Central City Hospital
 * Flash Museum
 * Julian Medical Supplies
 * S.T.A.R. Labs
 * Szrek Chemicals
 * Team Flash

December 1, 2013

 * S.T.A.R. Labs
 * Rebooted Legion
 * CCPD
 * Central City Hospital

January 27, 2015

 * S.T.A.R. Labs

April 29, 2016

 * S.T.A.R. Labs

Elseworlds Cold Open

 * Earth-90 Vigilante Group

Events

 * Assassination of Nora Allen
 * Particle Accelerator Explosion
 * Reverse-Flash's War
 * Capture of Pied Piper
 * Rescue of Joe West
 * Singularity
 * Metapocalypse
 * Attack on The Flash
 * Ambush on Zoom
 * Murder of Henry Allen
 * Race Against Zoom
 * Escape from Gorilla City
 * Conquering of the Speed Force
 * Rescue of Cecile Horton
 * Execution on Infantino Street
 * Battle Against Savitar
 * Enlightenment
 * Skirmish in the Speed Lab
 * Battle in the Mindscape
 * Metahuman Purge
 * Team Flash Time Hack
 * Reverse Time Hack
 * Elseworlds (Earth-90)

Species

 * Artificial Intelligences
 * Humans (Earth-1)
 * Humans (Earth-221)
 * Metahumans
 * Time Wraiths

December 11, 2013

 * Artificial Intelligences
 * Gorillas
 * Humans
 * Metahumans

January 27, 2015

 * Humans
 * Metahumans

April 19, 2016

 * Humans (Earth-1)
 * Humans (Earth-2)

May 23, 2017

 * Humans (Earth-1)
 * Metahumans (Earth-1)
 * Metahumans (Earth-3)
 * Time Remnants

Speed Force Visions

 * Humans
 * Metahumans (Earth-1)
 * Metahumans (Earth-2)
 * Metahumans (Earth-3)
 * Metahumans (Earth-19)
 * Time Remnants

Elseworlds Cold Open

 * Humans
 * Metahumans
 * Maltusians

Objects and Concepts

 * Breaches
 * CFL Quark Matter
 * Cicada Suit
 * Dagger Dampener
 * Dark Matter
 * Elongated Man Suit
 * Enlightenment Satellites
 * Flash Ring
 * Lightning Dagger
 * Nora West-Allen's Journal
 * Tachyons
 * Power-Dampener
 * Pulse Rifle
 * S.T.A.R. Labs Mobile Research Unit
 * Sally the Satellite
 * Savitar Armor
 * Speed Force Transmitter
 * Time Portal
 * The Flash Suit
 * Time Language
 * Vibe Suit
 * Reverb Goggles
 * Vibe Gauntlets
 * XS Suit
 * Gauntlets

December 11, 2013

 * Dark Matter
 * Firestorm Matrix
 * Firestorm Matrix Core
 * Reverse-Flash Suit

January 27, 2015

 * Dark Matter
 * Wheelchair
 * Savitar Armor
 * The Flash Suit (2015)

April 29, 2016

 * Breaches
 * Pulse Rifle
 * Speed Force Transmitter
 * The Flash Suit
 * Zoom Suit

May 23, 2017

 * Breaches
 * Killer Frost Suit
 * Savitar Armor
 * Speed Force Bazooka
 * The Flash Suit (Earth-1)
 * The Flash Suit (Earth-3)
 * Jay Garrick's Helmet
 * Vibe Suit
 * Reverb Goggles
 * Vibe Gauntlets

Speed Force Visions

 * Breaches
 * Dominator Drop Ship
 * Elongated Man Suit
 * Killer Frost Suit
 * Hoverchair
 * Jay Garrick's Helmet
 * Pied Piper Suit
 * Reverse-Flash Suit
 * Savitar Armor
 * The Flash Suit (Earth-3)
 * The Flash Suits (Earth-1)
 * Thinking Cap
 * Time Language
 * Vibe Suit
 * Reverb Goggles
 * Vibe Gauntlets
 * XS Suit
 * Gauntlets
 * Zoom Suit

Elseworlds Cold Open

 * Captain Cold Suit
 * Firestorm Suit
 * Green Arrow Suit (Earth-90)
 * Hawkgirl Suit
 * Hawkman Suit
 * Huntress Suit
 * Jesse Quick Suit
 * Obsidian Suit
 * Stargirl Suit
 * The Flash Suit (Earth-90)
 * The Ray Suit

Locations

 * Earth-1
 * Earth
 * North America
 * United States of America
 * Missouri
 * Central City
 * S.T.A.R. Labs Central City Facility
 * Flash Museum
 * Pipeline
 * Time Vault
 * Keystone City
 * Iron Heights Penitentiary
 * Speed Force

Prior to March 18, 2000

 * Earth-1
 * Earth
 * North America
 * United States of America
 * Missouri
 * Central City
 * Holly Drive
 * Allen Residence

December 11, 2013

 * Earth-1
 * Earth
 * North America
 * United States of America
 * Missouri
 * Central City
 * Central City Police Precinct
 * S.T.A.R. Labs Central City Facility
 * S.T.A.R. Labs Particle Accelerator
 * Time Vault

January 27, 2015

 * Earth-1
 * Earth
 * North America
 * United States of America
 * Missouri
 * Central City
 * S.T.A.R. Labs Central City Facility
 * S.T.A.R. Labs Particle Accelerator
 * Time Vault

April 29, 2016

 * Earth-1
 * Earth
 * North America
 * United States of America
 * Missouri
 * Central City
 * S.T.A.R. Labs Central City Facility
 * Earth-2

May 23, 2017

 * Earth-1
 * Earth
 * North America
 * United States of America
 * Missouri
 * Central City

Speed Force Visions

 * Earth-1
 * Earth
 * North America
 * United States of America
 * Missouri
 * Central City
 * Central City Police Precinct
 * S.T.A.R. Labs Central City Facility
 * Keystone City
 * Iron Heights Penitentiary
 * Earth-2
 * Gorilla City
 * Thinker's Sanctuary

Elseworlds Cold Open

 * Earth-90
 * Earth