Below is a list of characters, locations, etc., which originally appear in the DC Comics and other media prior to the episode's airing, by appearance.
Below is a list of characters who originally appeared in the DC Comics multiverse prior to the episode's airing, by appearance.
- Barry Allen/The Flash ("Pilot")
- Linda Park ("Pilot")
- Nora Allen ("Pilot")
- Henry Allen ("Pilot")
- Iris West ("Pilot")
- Tina McGee ("Pilot")
- The Ghost ("Ghost in the Machine")*
- James Jesse/The Trickster ("The Trickster")
- Captain Cold ("Captain Cold")
- Samuel "Sam" Scudder ("Done with Mirrors")
Comic book tie-in characters
In-universe fictional characters
Characters adapted as objects, concepts or groups
Fully renamed characters
- David McGee ("Out of Control") (fulfills the role of Jerry McGee)
- Desmond Powell/Nightshade ("Ghost in the Machine") (based on Wesley Dodds/Sandman, The Clipper and The Mikado)
- Curtis Bohannon ("Deadly Nightshade") (based on Mason Trollbridge, who took the mantle of second Clipper)
Characters from other sources appearing in comics
- Despite not being particularly based on any character of that nickname from the comics, Everett is named Kid Flash and is partially inspired by several people who used the nickname.