Jiminy acted as a conscience for Geppetto, in the form of a talking cricket. He was originally human, although the Blue Fairy turned him into his cricket form after he accidentally killed Geppetto's parents. He has also apparently been granted immortality so that he is able to stay by Geppetto's side throughout the years. Jiminy tries to steer Snow White and David Nolan off the path of war when they are presented with Regina's threat.
In Storybrooke, he is the town psychiatrist, Dr. Archie Hopper, who is easily intimidated and manipulated by Regina, the mayor of Storybrooke. Regina has her adopted son Henry having sessions with Hopper because she feels that he is distant. When Henry discovers that everyone in Storybrooke are storybook characters, Regina tries to get Hopper to stop Henry believing it, but when that has a negative effect on Henry, Dr. Hopper stands up to Regina and says that he will continue working with Henry, but in his own way, otherwise if Regina goes to court, Hopper can say whether or not Regina is a sufficient mother.
When the first Dark Curse breaks, he regains his memories of the Enchanted Forest. After Regina gets her dark magic back, he is one of the many Storybrooke citizens who try and escape over the town line, even though they will lose their memories. When Regina's mother Cora arrives in Storybrooke, she frames Regina by making it look like she killed Hopper. It is revealed that not even Cora killed Hopper, she only killed somebody else before disguising their corpse to look like Dr. Hopper. In actuality, Cora held Hopper as a prisoner so that Captain Hook could question him about Rumplestiltskin's weaknesses. However, when Hook becomes threatening, Hopper reluctantly tells him about Belle, Rumplestiltskin's girlfriend. Belle eventually finds Hopper and sets him free. He escapes, and tells Emma and her parents that Regina was not responsible, it was Cora. Emma and the others are shocked to see him alive, but thanks to him, they now know that Cora is in town.
When the second Dark Curse sends everyone in Storybrooke back to the Enchanted Forest, Jiminy is returned to his cricket form. However, the third Dark Curse sends everyone back to Storybrooke again, therefore giving him back his human form. The inhabitants of Storybrooke begin accusing Regina of casting the curse, including him. While Snow gives birth to Neal, he talks to Henry. Jiminy eventually marries Belle and Rumplestiltskin.
He attends the first town conference with Snow as the new mayor, and with an ice wall surrounding Storybrooke and Marian falling under a spell that freezes her, some of the other townsfolk start to blame Elsa. Hopper is reluctant to place his blame because he believes there is no proof. He sees that Snow has become stressed due to only recently becoming a mother and mayor, and explains that she doesn't have to be with Neal all the time, although Hopper does refrain from helping Snow put her baby pram into the back of her car.
It is revealed that, in the Enchanted Forest, Jiminy spent some time in Snow White's cleavage as a cricket.
Hopper and Pongo go for a walk to see Emma in the woods so she and Hopper can talk about her issues. He later schedules appointments with Emma, who shares her visions of death. Jiminy claims that Emma could be having an identity crisis. After learning that the Evil Queen is back, shades of his older timid self begin to show. A later appointment with Grumpy is interrupted by Emma, who fears that Regina may kill her, but he tells Emma that life can be about how she lives it, not how she ends it. In order to find out what Emma's visions entail, the Evil Queen kidnaps and impersonates Jiminy, holding him at Zelena's farmhouse where Zelena transforms him back into a cricket, although Jiminy is later rescued by Snow and David. Returned to his human form, he is visited by Hook, who wants advice on how to get David's blessing, as he wants Emma's hand in marriage but is racked with the guilt of having killed David's father. He also takes part in the dilution of Snow and David's curse, and unites Emma and Hook in marriage, just before they are all consumed by the Black Fairy's curse.
- Jiminy is based on the talking cricket from the story The Adventures of Pinocchio.
- He also alludes to Pongo's owner from The Hundred and One Dalmatians.
- In both human and cricket form, he carries an umbrella, which he considers to be his good luck charm.
- His surname, Hopper, is a reference to "hoppers", a term for crickets.
- He owns a Dalmatian named Pongo.
- S1, E01: "Pilot"
- S1, E02: "The Thing You Love Most"
- S1, E05: "That Still Small Voice"
- S1, E08: "Desperate Souls"
- S1, E16: "Heart of Darkness"
- S1, E19: "The Return"
- S1, E20: "The Stranger" (flashback)
- S1, E21: "An Apple Red as Blood"
- S1, E22: "A Land Without Magic"
- S2, E01: "Broken"
- S2, E02: "We Are Both"
- S2, E05: "The Doctor"
- S2, E10: "The Cricket Game"
- S2, E11: "The Outsider"
- S2, E17: "Welcome to Storybrooke" (flashback)
- S2, E22: "And Straight On 'Til Morning"
- S3, E07: "Dark Hollow"
- S3, E09: "Save Henry" (flashback)
- S3, E11: "Going Home"
- S3, E12: "New York City Serenade" (flashback)
- S3, E13: "Witch Hunt"
- S3, E19: "A Curious Thing" (flashback)
- S3, E20: "Kansas"
- S3, E22: "There's No Place Like Home"
- S4, E03: "Rocky Road"
- S5, E12: "Souls of the Departed" (flashback)
- S6, E01: "The Savior"
- S6, E02: "A Bitter Draught"
- S6, E03: "The Other Shoe"
- S6, E05: "Street Rats"
- S6, E06: "Dark Waters"
- S6, E12: "Murder Most Foul"
- S6, E13: "Ill-Boding Patterns"
- S6, E17: "Awake"
- S6, E20: "The Song in Your Heart"
- Bk 1: "Reawakened"