Caitlin StormVia googleIce QueenVia googleKiller FrostVia googleWinter WitchVia google
Caitlin's Earth 2 doppelgänger's name is Killer Frost. After meeting her, Caitlin is terrified of turning into her.
VisionVia googleReverbVia googleSageVia googleVibeVia google
Reverb is Cisco's Earth 2 doppelgänger's name before he's killed by Zoom. Cisco on the other hand prefers to go by Vibe.
Jesse QuickVia googleKid FlashVia googleThe RivalVia googleJohnny QuickVia google
Correct Answer - Johnny Quick
Though Johnny Quick is not a speedster we have seen on the show it's possible he could appear because he is a character in the DC universe. However I don't believe we will be seeing The Rival again...
Iris WestVia weheartitCaitlin SnowVia weheartitJoe WestVia weheartitCisco RamonVia weheartit
Yes, unfortunately when Barry accidentally runs to the future he sees the love of his life, Iris, killed by Savitar. Now he's fighting fate to stop that from happening.
Ronnie RaymondVia weheartitJulian AlbertVia weheartitWade EilingVia weheartitMason BridgeVia google
Not that it was fault as he was blacking out and being controlled by Savitar but yes Julian did turn out to be Doctor Alchemy.
Barry AllenVia weheartitHunter ZolomonVia weheartitRonnie RaymondVia weheartitJulian AlbertVia weheartit
Although they did have that super cute karaoke night, SnowBarry is not an official show ship.
Prism/Rainbow RaiderVia googleMistVia googleWeather WizardVia googlePlastiqueVia google
In the Pilot episode, Barry defeats Clyde Mardon who Cisco nicknames the Weather Wizard.
4Via google6Via google8Via google11Via google
Here we go... The Flash (Barry Allen), The Reverse Flash (Harrison Wells), The Reverse Flash 2.0 (Eobard Thawne), The Flash Earth 3 Version (Jay Garrick), Zoom (Hunter Zolomon), The Black Flash, Kid Flash, Trajectory (Eliza Harmon), The Rival, Jessie Quick, and Savitar.
The Speed ForceVia googleLightningVia googleThe particle accelerator explosion
The Speed Force
After going into the Speed Force to get his powers back, Barry realizes that the Speed Force the true source of his speed.
SupergirlVia googleLegends of TomorrowVia googleSmallvilleArrowVia google
Barry has guest starred on Arrow more than a couple times and he appeared on Legends during the Heroes Vs. Aliens crossover event. Barry also appeared on Supergirl before the show transferred to the CW when Barry ran so fast he made it all the way to Earth 38. Unfortunately Smallville ended before The Flash started, so no crossover there...
Grant GustinVia googleCarlos ValdesVia googleCandice PattonVia googleAndy MientusVia google
Grant Gustin was on Glee as the evil Warbler Sebastian Smythe, Carlos Valdes has released several EPs, and Andy Mientus was on Smash as Kyle Bishop and was also on Broadway. It has been confirmed that there will be a musical episode at some point. Hopefully with a crossover with Supergirl's Jeremy Jordan and Melissa Benoist.