- "I am Gideon, an interactive artificial consciousness."
- —Gideon To Barry Allen[src]
Gideon is an interactive artificial consciousness (A.I.) used by Eobard Thawne. It was hidden in the Time Vault inside S.T.A.R. Labs. Though it is used by Eobard, it was created by Barry Allen in the future. In order to manage her operating system, one needs the Reverse-Flash ring.
After he ran back in time to the year 2000 chasing Barry Allen, Eobard was told by Gideon that his connection to the Speed Force was no longer present and that he couldn't travel back in time to his home, leading him to steal Dr. Wells' identity.
Thawne used Gideon to record and catalog his notes about Barry Allen since he was struck by lightning and his heroics as "The Flash" ever since. He later used it to search for the Flash in future newspapers after his abilities were repressed by Blackout, to no avail. After Barry regained his abilities, Gideon was able to find the Flash in an article from 2024, reporting his disappearance in the crisis.
When Firestorm was about to go nuclear, Eobard entered his secret chamber (Time Vault) to retrieve a gun to shoot Firestorm. Gideon remarked that the weapon was rather crude. Thawne then had a change of heart and asked Gideon if the tachyon device could be converted into a quantum splicer. Gideon answered that it was theoretically possible, but doing so would delay his timetable.
When Barry, Cisco, and Caitlin discover the Time Vault, they met Gideon, who identified Barry, mentioning his future position as director of CCPD's CSI division and a founding member of something, but was interrupted by the latter before it could name the group. Barry then asked Gideon if it knew Thawne's true identity, but Gideon failed to understand his question. He then changed the question, asking what the Reverse-Flash was doing in their time. Gideon answered that he wanted to kill Barry as a child but he escaped, so he killed Barry's mother Nora out of anger. As Thawne approached, Cisco feared that Gideon would tell him of their discovery, so Barry asked Gideon if it could show them its operating system to erase its memory. However, Cisco took one look at Gideon's operating system and realized he couldn't do it, so Barry asked Gideon hesitantly to keep their meeting a secret. Gideon agreed, and much to the astonishment of Barry, explained that it was he (Barry) who created Gideon. As Barry whisked himself, Caitlin, and Cisco, out of the room, Thawne entered and was casually greeted by Gideon. He asked if everything was alright, and Gideon, complying with Barry's request, simply said that everything was fine.
Gideon later appears with Eobard (this time, in his original body) in a mysterious point in time.
- It identified the languages in the time vault to detect intruders.
- "Power Outage"
- "The Sound and the Fury" (voice)
- "The Nuclear Man" (voice)
- "Rogue Time"
- "Tricksters" (flashback)
- "The Trap"
- "Rogue Air" (mentioned)