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Caitlin Snow & (Killer) Frost

Dr. Caitlin Snow

Species: Human

Known Aliases: Caity

Played By: Danielle Panabaker

First Appearance: "The Man Under the Hood" (Arrow, 2x19)

Appearances: Arrow | The Flash | Flash vs. Arrow!note  | Heroes Join Forcesnote  | Invasion!note  | Crisis on Earth-X note  | Freedom Fighters: The Ray | Elseworlds note  | Crisis on Infinite Earths note 

An MD and bioengineering expert at S.T.A.R Labs, and The Medic for Team Flash, Caitlin is a highly intelligent, hardworking young woman. After losing her fiancé Ronnie in the S.T.A.R Labs particle accelerator explosion, Caitlin mourns her husband, believing that her personal and professional life is ruined. She finally finds a new direction in her life by helping Barry Allen, the Flash, in his crusade against the evil metahumans caused by the particle accelerator explosion, along with her co-worker and friend Cisco Ramon and the alleged Dr. Harrison Wells.

After the events of Flashpoint, she begins developing powers in the form of a second personality, an alter named Killer Frost. Though initially intimidated by her, the two begin to care for each other and co-exist as two separate people.

See Arrowverse: Earth-2 page to see Earth-2 Caitlin/Killer Frost

    Tropes involving Caitlin 
  • 10-Minute Retirement: At the end of Season 3, Caitlin decides to leave Team Flash in order to figure out who she is after spending the entire season struggling with her powers and her identity as Killer Frost. She leaves to go be a bartender but immediately joins back up with the team in the Season 4 premiere.
  • Action Survivor: Even before the show started, she and Cisco encountered Deathstroke on Arrow and survived.
  • Adaptation Dye-Job: She has brown hair in the series, whereas Caitlin Snow pre-becoming Killer Frost has white hair in the comics.
  • Adaptational Superpower Change: The show removes Caitlin Snow's heat vampirism, which was the main reason she was Driven to Villainy and sought a cure.
  • Afraid of Their Own Strength: Initially, Caitlin does not like her powers, or Killer Frost.
  • After Action Patch Up: Caitlin is The Medic and she tends to the injuries of all the members of Team Flash.
  • Ain't Too Proud to Beg: When Zoom kidnaps Caitlin and holds her hostage in his lair, Caitlin begs Zoom to let her go so she can go home to her friends. Zoom, of course, is against this and instead tries to extend a We Can Rule Together proposal to Caitlin.
  • Affectionate Nickname: Her husband Ronnie and her friends sometimes call her "Cait". Killer Frost often refers to her as "Caity".
  • All-Loving Heroine: Caitlin always tries to see the good in people as much as possible, including her Killer Frost persona. She likes to use love, empathy and compassion to get through to others and always gives people second chances. Subverted in some cases such as Zoom and Grodd where even she thinks they're beyond help.
  • Aloof Dark-Haired Girl: She has a rigid demeanor since the aftermath of the Particle Accelerator accident, though it gradually disappeared around the end of the second episode.
  • Alphabetical Theme Naming: She and Mrs. Clarissa Stein are the Love Interests of the two earlier people that compose Firestorm.
  • And Starring: During her Early-Bird Cameo on Arrow, she gets the "And" billing in the regular guest star line-up. Once The Flash (2014) starts airing, though, she moves to the "Special Guest Star" line-up along with the rest of the cast whenever they appear.
  • Anger Born of Worry: She was initially angry at Barry for putting himself at danger for what she saw as no good reason, but it's stated that the only other person to have made her that angry was her late fiancee, suggesting she cares about him more than she lets on. She starts to mellow out after the second episode.
  • The Atoner: After hurting her friends while she was Killer Frost in Season 3, Caitlin is genuinely remorseful and wants to make amends for what she has done.
  • Badass Bookworm: In her very first appearance on Arrow, she and Cisco use their brains to outsmart Deathstroke, who's been terrorizing Team Arrow for weeks.
  • The Bartender: After leaving Team Flash at the end of Season 3 to go on a self discovery, it was revealed that Caitlin was working as a bartender at the start of Season 4.
  • Beware the Nice Ones: Caitlin is friendly and peaceful most of the time, but make no mistake: if you press the wrong buttons and irritate her, she will throw hell on you.
  • Blessed with Suck: Caitlin's powers come at the price of losing control thanks to a Split-Personality Takeover.
  • Brainy Brunette: Caitlin is a brilliant scientist with expertise in many fields.
  • Break the Cutie: Caitlin had a promising career in bioengineering and was about to marry the love of her life. Then the particle accelerator exploded, her career was in shambles, her fiancé died that night and her boss was put in a wheelchair. Barry coming back from his coma and becoming the Flash gave her life new meaning and she found out that her fiancé was still alive (and she would finally marry him later), but then her boss turned out to be a murderer and her husband sacrificed himself to save her and the city. And that's just the first season.
  • Broken Ace: She's as brilliant as she is beautiful, and yet since the traumatic night of the partical accelerator, her confidence in both her professional and personal life has been shaken, given her reputation as a doctor and bioengineer has been heavily tarnished in the fallout against S.T.A.R Labs, and her love life has been lacking, after the death of her husband Ronnie, having not had the best choices in men following. Add on top of that her discovering a violent alter within her called Killer Frost, though after the latter's Heel–Face Turn, she's come to love her like a sister, and her fractured relationship with her mother (which takes a turn for the better after her father kidnaps them). However thanks to the love from her Team, she's slowly but surely growing out of this.
  • Broken Bird: The tragic loss of her husband Ronnie caused to fall into a Despair Event Horizon before the start of the series. It takes her time to come out of it.
  • Brought Down to Normal: In "Lose Yourself", Caitlin loses her ice and cold powers after Ralph who was possessed by DeVoe absorbs them from her. It's later revealed he used a mental block against Killer Frost instead of take her away outright. She’s once again this trope, as she and Frost now have split bodies.
  • But Now I Must Go:
    • After betraying Savitar in the Season 3 finale Caitlin admits that she doesn't know who she is anymore and decides to leave in order to find out. As it turns out, "finding herself" amounted to becoming a bartender and being back to square one: still repressing Killer Frost, though it appears the two of them have a better understanding.
    • In Season 8, After the death of Frost, and Barry finally convincing her there is no way to bring her back from the dead, Caitlin decides to move back home with her mother, leaving a message to her friends she needs some time to adjust, and doesn't know when or if she will return.
  • Came Back Wrong: Caitlin is on death's door in "Abra Kadabra" but she is brought back after Julian rips off her necklace. Unfortunately, she comes back as Killer Frost entirely.
  • Can't Hold Her Liquor: She's not the best at drinking.
  • Cartwright Curse: She lost Ronnie twice, and her blossoming romance with "Jay Garrick" was abruptly cut short when Zoom kills him and takes him back to Earth-2, and she learns who the man she was falling for really was. She also had an interest in Julian Albert after he became nicer, but her ordeal with Killer Frost being in her life led her to turn it down to focus on herself.
  • Celebrity Paradox:
  • Clothing Reflects Personality: Caitlin commonly wears somber or darker colors, highlighting her generally guarded and somber personality. Clothing colors that she's often seen wearing are blue, white, and black.
  • Color Motif: Her clothes are mostly composed of white, black, blue or any combination of them.
  • Combat Medic: She's a trained doctor as well as a bioengineer, and is a seasoned Action Survivor. This trope becomes more prominent for her after becoming a metahuman. At one point she even used her medical knowledge while fighting Barry.
  • Composite Character: She's a S.T.A.R. Labs scientist like the third Killer Frost, from whom she also takes her name, but her romantic backstory with a character who becomes Firestorm is incorporated from Crystal Frost, the first Killer Frost. As Killer Frost, her initial characterization is incorporated from Magenta's original relation to Wally West: an ally with powers attached to an aggressive alter who blames the hero for their condition, and whose initial plot beats follow increasing instability as she is forced to use those powers in tenser and tenser situations. Her being forced to use her powers (and risk turning evil) to disarm a superweapon is even taken almost directly from one of Magenta's early appearances.
  • The Confidant: Caitlin often serves as this to Team Flash, especially in the first season. She gives advice and reassurance to those who need it. Cisco in particular discloses his problems to her, since she is like a sister to him.
  • Conflicting Loyalty: She refuses to believe that Thawne really is the Reverse-Flash, which puts her in conflict with Barry and Cisco. That is until she sees the remains of the real Harrison Wells and Thawne's secret chamber.
  • The Conscience: Plays this role to Hunter Zolomon/Zoom of all people in Season 2 because of his Villainous Crush. She acts as a Morality Chain for him and tries to prevent him from harming innocent people.
  • Covert Pervert: She has moments.
    • In "Crazy for You", in an inebriated state, she says she wouldn't mind if Barry took a peek under her dress.
    • In "Flash of Two Worlds," she subjects "Jay" to a full body scan, claiming she was "being thorough."
  • The Cutie: When she's allowed to, she has her moments.
  • The Cynic: Caitlin used to have a very pessimistic and cynical view on life. Thankfully, being on Team Flash has made her more open and brought her kind personality to light. This eventually shifts over to being Killer Frost's shtick.
  • Damsel in Distress: Caitlin gets kidnapped a lot, even after she has Frost as backup. It's happened once a season, save for the 3rd (which technically counts if you consider Killer Frost holding her mentally captive at various points).
    • Season 1: Leonard Snart and Mick Rory kidnap her in the Season 1 episode "Revenge of the Rogues".
    • Season 2: Grodd kidnaps her in "Gorilla Warfare". Then Zoom kidnaps her near the end of the season, and unlike the rest, it exceeds a single episode. This sets-up a Rescue Arc towards the end of season.
    • Season 4: She gets taken by Amunet in "Don't Run" and by Earth-X's Laurel Lance in "Fury Rogue".
    • Season 5: She and her mother are abducted by her father's own Superpowered Evil Side, Icicle, in "Snow Pack".
  • Dangerous Forbidden Technique: Her ice powers work like this in season 3, as every time she uses them she runs the risk of being completely taken over by her Superpowered Evil Side.
  • Decomposite Character: Subverted. Her traditional Supervillain role went into her Earth-2 counterpart, but she eventually acquired a Superpowered Evil Side anyway.
  • Defrosting Ice Queen: She begins warming up over the first few episodes.
  • Disappeared Dad: Her father allegedly died of ALS prior to the series start. The fifth season reveals otherwise, until he dies for real in front of her and her mother.
  • Does This Remind You of Anything?: Her relationship with Zoom in the last stretch of season 2 is akin to a victim of Domestic Abuse - hoping to make him change, being held somewhere against her will, told by her assailant how much she means to him, and threatened with death if she tries to leave.
  • Dude Magnet: In the first three seasons, Caitlin has gotten a new love interest in each of them.
  • Early-Bird Cameo: Guest starred on Arrow before The Flash (2014) aired.
  • Eating the Eye Candy: Whenever an attractive man is around (i.e. Eddie, Ray, Hunter, Oliver), sometimes even being villains, Caitlin usually can't help herself from staring.
    "Jay": I even subjected myself to a full body scan!
    (Barry and Iris glare at Caitlin)
    Caitlin: [meekly] I was being thorough!
  • Emotionless Girl: Subverted. At first, Caitlin came of as icy, cold and aloof, but once she started helping Barry as The Flash, she starts to open up to others more.
  • Empowered Badass Normal: In Season 1 and 2, Caitlin is a regular human and an Action Survivor with no meta human abilities. In Season 3, it was implied that Cailtin's ice/cold powers activated due to Barry creating Flashpoint. However, it's revealed at the end of Season 4 that her meta human abilities have been present all along and they were dormant.
  • Enemy Within: Zig-Zagging Trope. At first, it seemed that Killer Frost was fighting for control of Caitlin's body, who feared her Superpowered Evil Side and repeatedly stated she'd rather die than let her take over. When Caitlin goes on a Journey to Find Oneself, it seems like she and Killer Frost eventually come to an understanding.
  • Evil Me Scares Me: Upon finding out that her alter ego Killer Frost is a blood thirsty and ruthless individual, Caitlin goes to the lengths to get rid of her powers out of fear that she would turn into Killer Frost and hurt someone.
  • Face–Heel Turn: Towards the end of Season 3, Caitlin becomes Killer Frost and becomes The Dragon for Savitar. At the end of Season 3, she becomes The Starscream and turns against Savitar. In Season 4, she does a Heel–Face Turn and joins Team Flash.
  • Fallen Hero: After Caitlin "dies" at the end of "Abra Kadabra", she comes back as Killer Frost after Julian rips off her Power Limiter necklace. She turns on Team Flash and becomes The Dragon for Savitar, the Big Bad of Season 3. She inverts this trope at the end of Season 3 when she betrays Savitar and sides with Team Flash. In Season 4, she becomes The Atoner and tries to fix things with her friends after trying to harm them.
  • Fan Disservice: You wouldn't think this would apply with someone as gorgeous as Caitlin, but...
    • In the Season 1 episode Crazy for You she wears a skimpy black dress that could give Iris, Laurel or Felicity a run for their money. Unfortunately, the scene ends with her getting drunk and throwing up.
    • Her shower scene in Season 3 episode The New Rogues shows her unintentionally freezing the water and turning her skin ghostly pale, her lips icy blue and her hair white. She is terrified of what is happening.
  • Fire/Ice Duo: While she never quite got there with her fiancée/husband Ronnie Raymond who was one half of Firestorm, due to Caitlin yet to develop her ice powers and Ronnie’s early death, this pairing is still alluded with Ronnie describing the two of them as being "like fire and ice". Their Earth-2 counterparts however play it straight with both their powers showed off and are Happily Married to each other.
  • Foregone Conclusion: The reason there are no spoiler tags for anything pertaining to Killer Frost.
  • Foreshadowing:
    • She refers to Ronnie and herself as "like fire and ice." This is an allusion to Ronnie becoming the superhero Firestorm and Caitlin eventually becoming the supervillain Killer Frost.
    • Cisco confesses to Caitlin that he met her doppelgänger, an Ax-Crazy Ice Queen metahuman, and he begins to see Caitlin acting eerily similarly to her. Caitlin knows what would happen though, if she didn't suppress her feelings.
    • In one of Hunter Zolomon's attempts to make Caitlin join his side, he tries to make her see that he, Killer Frost, and her aren't so different.
    • When Harry scans dark matter readings on Caitlin, there's none present. While it was suspected to be retconned due to Flashpoint, it also foreshadows the fact her Meta powers don't come from dark matter.
  • Generation Xerox: She's a lot like her mother in terms of personality and history, throwing themselves into work when tragedy hits and becoming cold as a result. Bonus points for both women having lost their husbands twice over at various points in their life.
  • Girliness Upgrade: Compared to the comics, Caitlin tends towards fashionable dresses and as Killer Frost, has more of a Minidress of Power at first and her hair is long and feminine. In the comics, she's got short hair with a punk-rock style and tends towards a more tomboyish style.
  • Has a Type: The men in her life (Ronnie Raymond, Hunter Zolomon, Julian Albert, etc.) have a background in science.
  • The Heart: Her role in Team Flash, being The Medic and the lone female member until Iris joins.
  • Heterosexual Life-Partners: Eventually comes to be this with Iris.
  • Horrible Judge of Character: She thinks that Henry Hewitt will be a great successor for Ronnie regarding the Firestorm matrix, and doesn't have a good opinion about Jax, because Hewitt is a scientist and Jax has nothing in common with Ronnie or Stein. This... did not go out so well.
  • Hypocrite: Caitlin seems to have a double standard when it comes to the moral standards she applies to herself and moral standards she applies to others; however, this is not addressed in the narrative.
    • In an attempt to get rid of Killer Frost, she aids and abets in a meta-human-trafficking business, run by Amunet Black, going so far as to work the bar of the underground business and allow Killer Frost to be used as muscle to capture metas, who were then bought and sold.
    • In "King Shark vs. Gorilla Grodd," Caitlin (along with Cisco) strongly oppose Barry using the meta-human cure against King Shark in self-defense, because Lamden hadn't consented. Caitlin, in that very same episode, places Grodd in a medically-induced coma, with the help of Lyla Diggle, without Grodd's consent. Her actions were also done in, and justified by, self-defense. However, this double standard is not commented on within the narrative.
  • Iconic Sequel Character: Introduced to the Arrowverse during its second year before becoming a main character on her own show during the third.
  • Idiot Ball: She was planning to go to Thawne's house to demand info about him being the Reverse-Flash. Fortunately, Barry stops her at the last second.
  • I Just Want to Be Normal: Caitlin initially doesn't want her powers, seeking Alchemy and then stealing the Philosopher's Stone to see whether she could remove them. She ends up changing her mind about Killer Frost from Season 4 onwards, when she gets to know her alter ego better and realizes that she can do some good in this world.
  • Impersonating the Evil Twin: She makes a Dead Person Impersonation of Earth-2 Killer Frost to distract Black Siren during season 2.
  • Improbable Age: It's revealed in Season 6 she was born in 1989, which means that she was already a professional neurosurgeon and scientist at the age of 24 or 25 when she debuted (Panabaker was 26 at the time). In the United States, it takes at least seven years of residency before neurosurgeons can begin applying for a license, on top of the eight years of higher education to become a neurosurgeon in the first place, so Caitlin must have graduated from high school at the age of 10 or less.
  • In Spite of a Nail: Her Flashpoint timeline self is still a doctor, just not the kind she was before and after. Also, despite her Earth-2 doppelgänger being evil and not herself, she still became Killer Frost.
  • Intergenerational Friendship: With Martin Stein and Harry Wells.
  • It Runs in the Family: She and her parents are all doctors.
  • Journey to Find Oneself: After helping to defeat Savitar she admits that she is no longer Killer Frost. But she is also no longer Caitlin Snow either and she decides to leave Central City until she can figure out who she is now. She returned and at first punched the Reset Button, as she was still fighting off Killer Frost. Eventually the two sides came to an understanding.
  • Killed Off for Real: In Season 9, is made very clear that Caitlin died in the experiment to bring back Frost, and that Khione was born from. Subverted when she returns alive in the series finale.
  • Leg Focus: Her outfits, from Pencil Skirts to Mini-Skirts, tend to focus on showing off her legs. Even Killer Frost lampshades this at one point.
    Cisco: So you've gone full on Killer Frost? New threads and everything.
    Caitlin/Killer Frost: (smugly) No more pencil skirts for me!
  • Married to the Job: Everyone notices she has very little life outside of her job. It's partly because she's naturally a workaholic, and partly because she's working to forget about Ronnie in the first season.
  • Meaningful Name: The moniker "Snow" alludes to more than a chilly disposition. Takes another notch when she gains her ice powers.
  • The Medic: To Team Flash, given she's the only one who is a trained and licensed MD.
  • Mommy Issues: Caitlin has a very troubled and strained relationship with her mother Carla. Her tension filled relationship with her helped to shape who Caitlin was. They appear to reconcile on some level, but uncertain if it's retained Post-Crisis.
  • Morality Chain: For Ronnie when he was still unwillingly fused with Prof. Stein as Firestorm, much like how Stein's wife Clarissa was for the latter during the ordeal. She later becomes one for Hunter Zolomon AKA Zoom of all people, due to her strong physical resemblance to his mother Ashley. She was also one along with Cisco for Eobard Thawne/Reverse Flash as "Harrison Wells". Eobard was genuinely fond of Cisco and Caitlin but that didn't mean he wouldn't put them in danger for his own benefit despite his fondness for them.
  • Ms. Fanservice: Not as much as say Iris, most likely given her profession, but she is a classically beautiful woman who happens to have an affinity for Mini-Skirts, and is shown to wear some more revealing attire when off the clock. And when she turns into Killer Frost...
  • Mythology Gag: She mentions Ronnie used to say they were "fire and ice", a nod to her alter-ego in the comics, ice-based villain Killer Frost. In "Flash vs Arrow" she also wears a necklace with the cold front weather symbol.
  • Never Hurt an Innocent: Caitlin plays this straight. Killer Frost does not.
  • Nice Girl: Despite her, ahem, frosty demeanour at times, Caitlin is undoubtedly one of the nicest characters in all the Arrowverse.
  • No Place for Me There: Caitlin doesn't want to stay with her friends if she becomes Killer Frost. When Killer Frost is in control, she suggests they let her go.
  • The Not-Love Interest: Since Season 1, Caitlin has been best friends with Barry and Cisco and works with them at STAR Labs and as a superhero, but she never shows a love interest in either.
  • Now, Let Me Carry You: She pretty much says this verbatim to Cisco in Rogue Time to convince him to let her lend support at the family gathering he must attend.
  • Oh, Crap!: When she realizes that "Wells" is Thawne, who also is the Reverse-Flash. However, she forgets when Barry hits the Reset Button.
  • Omnidisciplinary Scientist: Honest Trailers say it best: Caitlin Snow, a doctor/scientist/bioengineer/hacker/hematologist/chemist...
  • One-Steve Limit: Shares the same surname with Star City News 52 reporter Bethany Snow. They are unrelated as far as we know.
  • One True Love: Ronnie Raymond. Like Barry and Iris, they were also married on an alternate earth. While Caitlin was eventually able to move on from Ronnie's death and had relationships after him, there is no question that he was the love of her life, and that she will always love him for as long as she lives.
  • Opposites Attract: Caitlin describes her and Ronnie this way. He was more fun, while Caitlin was more serious.
  • Other Me Annoys Me: She thinks that her Earth-2 counterpart is a bitch, which isn't entirely false.
  • Out of Focus: Of the second half of season 6, due to Panabaker's pregnancy.
  • Overshadowed by Awesome: Starts feeling this way towards her alter ego after Killer Frost helps to repel the Earth-X invaders. She snaps out of it after a motivational speech from Amunet.
  • Perpetual Frowner: Subverted. In the first episode, Barry notes to Caitlin that she hardly smiles or looks happy. Caitlin says that she has no reason to smile after undergoing the tragedy of losing her fiancé and her reputation and career as a bioengineer being tarnished after the particle accelerator exploded. However, after helping Barry out as The Flash, she starts to smile a lot more.
  • Platonic Life-Partners: With both Cisco and Barry.
  • Power Limiter: Caitlin wears Cisco's metahuman power-dampening cuffs and bracelets to keep her powers in check and to suppress Killer Frost. She later receives a Mid-Season Upgrade in the form of a pendant.
  • Red Oni, Blue Oni:
    • She's the Blue to Cisco and Frost's Red.
    • Ronnie also described her as the ice (Blue) to his fire (Red).
  • Red Herring: Her Frost persona and ice powers appear to be one of the many alterations of Flashpoint, but Season 4 reveals she's had them since childhood.
  • Refusal of the Call: At first, she doesn't approve of Barry using his powers to help ordinary citizens, instead thinking they should be used exclusively to contain rogue meta-humans. She changes her tune by the end of the second episode.
  • Related in the Adaptation: In the comics, Firestorm and Killer Frost are enemies. She and Ronnie got married in the Season 1 finale.
  • Secret-Keeper: Another one of the Flash's inner circle.
  • She Cleans Up Nicely: Barry was quite surprised that she showed up to their Not a Date in a Little Black Dress. Caitlin mentions that she doesn't dress up like a school principal every day.
  • She's Back: Caitlin's return in Season 4. Cisco makes it clear she's "our Caitlin" and not Killer Frost. Killer Frost is still around, just far less hostile.
  • Ship Tease:
    • With Barry. Originally, the writers considered Barry and Caitlin as a couple, delaying the union of the Barry / Iris couple. This explains why the two have many scenes in the early seasons suggesting an attraction between them:
      • Cisco comments that the only person who ever made her that upset was her late fiancé, Ronnie.
      • In Things You Can't Outrun, they spend a good deal of time together, and he helps her with panic attacks provoked by the thought of the Particle Accelerator. The comic tie-in implies that she's attracted to him.
      • Crazy For You is pretty much an entire episode of Barry/Caitlin Ship Tease.
      • When Everyman takes Barry's form and kisses her, she reciprocates.
      • At the start of Season 2, Caitlin tells Barry that she couldn't leave Central City with Ronnie because that would have meant she would have left S.T.A.R Labs, "Wells"... and Barry.
      • In the same episode, Barry refuses to watch Thawne's last will video, but he finally does it when Caitlin offers to watch it together.
    • With Cisco, there are several ship tease moments, like the time he was injured and woke up saying her name.
      • A majority of the time, when both are single, the two act as each others plus ones/escorts to major events.
      • In Things You Can't Outrun, a flashback to the explosion reveals that the only way Ronnie convinced Cisco to essentially let him die was that, if not, it would be Caitlin who died.
      • There are several flashbacks with them together, to the accident, and to when he starting working at S.T.A.R Labs. He declares that "she seems nice" while gazing after her with a starstruck look.
      • In The Man In the Yellow Suit, Cisco holds Caitlin and comforts her as she cries about Ronnie.
      • In Revenge of the Rogues, Cisco is the one to rescue Caitlin. She hugs him because she thought she was going to die, but he says, "Not while I'm around."
      • Caitlin is Cisco's date to his brother's birthday party in Rogue Time, and Dante flirting with her there parallels him stealing Cisco's crush in high school.
      • In Rogue Air after discovering that Cisco and Lisa Snart kissed, she immediately responds in disgust, shock and disappointment, and continues to sour up when Cisco makes a lighthearted gest on possibly wanting to kiss her again, even though she's a criminal and he's one of the good guys.
      • In King Shark Cisco is the one most worried that Caitlin's coldness both metaphorically, and literally, after Jay's death, could be indicative of her turning into Earth-1's Killer Frost.
      • The two of them dancing together, rather sporadically, but having fun all the same, during Team Flash's night out in Trajectory.
      • The first person Caitlin opens up to about her time as Zoom's hostage in Invincible is Cisco, and she breaks down in his arms.
      • After Dante's death, it's revealed that Caitlin slept on Cisco's couch to keep him company.
      • In Shade, when she finally can't hold it in anymore, about her transforming into Killer Frost, the first and only person she intended to reveal it to was Cisco.
      • Later on, when the group is planning on the outdoor movie, she openly refers to her and Cisco being each others dates for the night.
      • In "The Present," when Savitar is manipulating Cisco, with images of Dante, Caitlin is the one who talks him down.
      • She immediately turns on Savitar when he goes to attack Cisco, she blasting him with ice in Cisco's defense.
    • She also shows a lot of interest in "Jay", that is until her's actually revealed to be the Serial Killer Hunter Zolomon/Zoom, effectively ending whatever feelings she had for him.
      • The first scenario the two spend time with one another, Caitlin does a "thorough" full-body search on "Jay", with the implication she was admiring him after she and Iris call him "an interesting specimen."
      • When it looks like "Jay" might return to Earth-2, Caitlin gives him a laundry list of reasons to stay. Cisco is fully aware of why she's doing so.
      • They Almost Kiss in "The Darkness and the Light", before Dr. Light attacks.
    • She and Ralph have a lot of hints of this in their interactions, suggesting a mutual attraction to one another, to the point that Word of God confirmed that the two were originally meant to be coupled together during season 4, before they decided to lay off putting Caitlin in yet another relationship so quickly.
  • Shipper on Deck: She is this for Barry and Iris.
  • Single Woman Seeks Good Man: All of her known love interests were because she was drawn to how decent they were.
    • Ronnie was a Nice Guy who helped her be more open and was her husband for a time. His first heroic sacrifice made her love him even more.
    • She fell for the man they thought was Jay Garrick because he was the hero of Earth-2 and wanted to help defeat Zoom despite losing his powers. This is turned around when it turns out his real name is Hunter Zolomon, and he is Zoom, not to mention a serial killer.
    • Averted with Julian, she was able to initially see good man under his hostile personality, and while she did seem to like him and was on the cusp of falling in love, Caitlin's dealing with Killer Frost in her life put a damper on things. She abstained from taking his meta antidote, and gently turned him down when he admitted his love for her one last time.
  • The Smart Girl: Caitlin is a highly intelligent scientist; she has a medical degree, but she's also an expert in many other scientific fields.
  • The Smurfette Principle: At first she is the only female member of Team Flash, aside from Felicity's occasional stints, until Iris joins once she learns Barry is the Flash.
  • Spell My Name With An S: Caitlin's name in certain episode's subtitles is often misspelled as "Caitlyn".
  • Star-Crossed Lovers: With Ronnie, she was happily engaged to him before he seemingly died when the Particle Accelerator's core went critical and exploded with him trapped in the pipeline. Later on however she discovers him to be the psychotic and dangerous Burning Man, and it only goes downhill for the two of them from there, ending with him dying on the day of their Wedding.
  • Steven Ulysses Perhero: Caitlin Snow, to match her An Ice Person powers.
  • Strong Family Resemblance: She has a very strong physical resemblance to her mother.
  • Sugar-and-Ice Personality: She has more sugar than ice, compared to Frost.
  • Tempting Fate: Several times in season 2.
    • After Cisco reveals that he has powers and that he got them from Thawne through the particle accelerator explosion, he fears that he might become as evil as Thawne.
    Caitlin: Cisco, I don't think any of us would become evil, if we all of the sudden got powers, even if they were from Dr. Wells.
    • When Caitlin returns to being an Ice Queen for a while after "Jay" died in front of her eyes, Cisco is afraid that Caitlin will turn into her Earth-2 doppelgänger.
    Caitlin: Cisco, you need to stop worrying about me. I may be sad, I may want to be alone for a little while, but I promise you, Killer Frost will never exist on this Earth, okay?
  • Tritagonist: One could make a strong argument of her being this. While Barry and Iris are clearly the main leads, Caitlin's storyline regarding her family, her love interests, Killer Frost, her background, as well as the mystery of where her alter comes from, has and continues to receive the most series wide development. Also, she has the third most amount of episodes (Barry having appeared in every episode, and Iris missing only two episodes) missing only three episodes of the series thus far note , and Panabaker has been the third billed actor after Gustin and Patton, since the show premiered. The departures of two other regular cast members in Season 7, Carlos Valdes (Cisco Ramon) and Tom Cavanagh (Harrison Wells) also cement Caitlin's position as the Tritagonist.
  • Undying Loyalty: Even though the explosion ruined her career and killed her fiancé, she's still working for Thawne and S.T.A.R Labs. That is until she learns about the Reverse-Flash.
  • Vague Age: Averted. "The Death of Vibe" reveals her birthdate to be February 28, 1989.
  • Widowed at the Wedding: She and Ronnie finally wed, but mere hours after their vows, Ronnie dies while helping Barry disrupt the Singularity over the city, being sucked inside it.
  • Workaholic: She's naturally intensely focused on her job and doesn't really have much of a life outside of S.T.A.R. Labs.
  • You Are Better Than You Think You Are: It goes both ways. Caitlin says that Frost has the potential to do good despite her reservations and Frost tells Caitlin that she's perfect the way she is despite her feeling inadequate as a person.

"It's 'Frost'. I'm rebranding."

Species: Metahuman

Known Aliases: Killer Frost, Khione

Played By: Danielle Panabaker

First Appearance: "Monster" (The Flash, 3x5)

Appearances: The Flash | Crisis on Earth-X note  | Elseworlds note  | Crisis on Infinite Earths note 

When Caitlin’s father ran experiments to cure his amyotrophic later sclerosis, he discovered she inherited the disease from him. Administering a cure, it caused her to develop Metahuman powers in the form of an alter, which would begin manifesting itself as a separate conciousness representing the repressed anger she's had over the various traumas and tragedy she's experienced. While Killer Frost at first attempted to destroy The Flash and his allies, eventually she and Caitlin came to an understanding; as such, Killer Frost became an ally, often showing up when Caitlin feels strong emotions or urgently needs her help.

During a battle with season 4 Big Bad The Thinker, he temporarily disabled Caitlin's access to Killer Frost, which is restored by season 5. In season 6, Caitlin allows Killer Frost to be the host much more frequently to live her own life, deciding to drop the "Killer" from her name and become a genuine hero. By season 7 after a meta-incident, she actually splits off from Caitlin, becoming her own person, with her own body.

See Arrowverse: Earth-2 page to see Earth-2 Caitlin/Killer Frost

    Tropes involving Frost 
  • Adaptational Attractiveness: In the comics, the Caitlin Snow version of Killer Frost has the most menacing appearance due to a punk undercut and tomboyish dress sense. This version has a very feminine appearance akin to the Crystal Frost and Louise Lincoln versions.
  • Adaptational Heroism: Played with, in that she goes through a Face–Heel Turn but reverts after. Though, even in the comics, the Caitlin Snow incarnation of Killer Frost was always an Anti-Villain at worst (in fact, thanks to removing her 'heat vampirism', the show makes her villain turn a case of Adaptational Villainy by removing the tragic circumstances that make her a villain), and similarly became a hero during DC Rebirth. However, the show makes a point that despite her name, Caitlin never successfully kills anyone, while in the comics, she killed the HIVE agents who did this to her and an innocent group of campers just to survive.
  • Adaptational Modesty: Played with; she eventually starts wearing a less revealing outfit, but originally she showed far more skin than her comic counterpart, whose main point of revealing attire is her midriff-exposing top, and even that is usually covered by a thick coat.
  • Adaptational Personality Change: Though in the comics she's an Anti-Villain too, there's no alter; rather, 'Killer Frost' and 'Caitlin Snow' are the same entity, and Caitlin merely has an overpowering hunger for human body-heat, being Killer Frost permanently. The Killer Frost persona seems to be closer to the previous Killer Frosts, not Caitlin.
  • Adaptational Villainy: At her worst, Caitlin Snow in the comics was Driven to Villainy because she needed to find a cure, and the majority of her evil deeds are in the backstory of her introduction. Though she has killed people, it was only because she needed to in order to survive. The show removes her heat vampirism, and thus there's no actual logical reason for why she turns on the team and attacks them, she just does because the Killer Frost alter was violently defensive and aggressive.
  • Adaptational Wimp: Her being Weak to Fire is the exact opposite of how Caitlin interacts with heat in the comics. Her weakness is actually other cold environments, as she needs to drain heat to survive; large sources of heat would give her more power and actually help sustain her.
  • Anti-Hero: She becomes one by Season Four, of the Good Is Not Nice variety. She's still very rude and at times reluctant to get into heroics, but can be swayed to help Team Flash without too much trouble.
  • Ascended Extra: In the comics she was a reoccurring villain, while here she's a main character.
  • The Atoner: In Season 7, Frost decides to give herself up for the crimes she did commit when she and Caitlin were one person.
  • Awesomeness by Analysis: It is heavily implied that she quickly figured out how to use her powers mainly by watching her Earth-2 doppelganger in action during their brief encounter.
  • Badass Longcoat: She used to wear dark blue one in Season 3 but she later got a shorter light blue jacket in Season 4.
  • Bad Powers, Good People: Caitlin believes her other persona is good deep down, but her temperament and willingness to use lethal force makes it difficult.
  • Beauty Is Bad: Subverted. As Killer Frost, Caitlin is very beautiful and a Ms. Fanservice to boot, but was originally a villainess who didn't have good intentions. However, Killer Frost ultimately does a Heel–Face Turn and her costume becomes modest.
  • The Big Gal: Post-Heel–Face Turn, Frost is mainly summoned whenever Team Flash is in need of raw power to take down a threat that Barry’s speed alone is unable to handle.
  • Big Sister Instinct: Split Personality case, as she is extremely protective of Caitlin.
  • Blue Is Heroic: Her entire outfit is made up of the color blue and she becomes an Anti-Hero in Season 4 once she joins the heroic side.
  • Book Dumb: She lacks any of Caitlin's know-how with medical knowledge so she opts out with her when it's needed.
  • Bright Is Not Good: She has Mystical White Hair, ultra pale skin, Icy Blue Eyes, wears the color blue, is cryokinetic, and is Caitlin's Superpowered Evil Side. Downplayed after her Heel–Face Turn, she's still an Anti-Hero.
  • Brutal Honesty: She rarely minces her words.
  • Character Development: Season 6 delves deep into it, with Caitlin allowing her to inhabit their consciousness more often.
  • Characterization Marches On: At first, Killer Frost appears to just simply be Caitlin but with her negative emotions and personality traits amplified. But it isn't until later on it's established that they're two separate personalities.
  • Clothing Reflects Personality: Her attire is commonly blue and dark blue which is fitting since she has cold and ice powers and ice is associated with the color blue.
  • Cold Ham: No pun intended. She can act very expressive in her behavior and actions, doubling down on the sarcasm compared to Caitlin.
  • Color-Coded Elements: She wears the color blue and she has ice/cold powers.
  • Creepy Blue Eyes: As Killer Frost, Caitlin undergoes an Eye Color Change where she gets Icy Blue Eyes that can be extremely chilling and scary if she's giving a Death Glare.
  • Dark Action Girl: Downplayed as she undergoes a Heel–Face Turn.
  • Dark Magical Girl: Until she turns more heroic in season 4.
  • A Day In The Lime Light: More like a season, Season 6, with Caitlin's blessing, Killer Frost will be taking the reigns of their body more often, giving her a chance to have life experiences outside of the battlefields, and explore her character much more.
  • Deadpan Snarker: Killer Frost snarks a lot.
  • Death Glare: She gives plenty of these when she is Killer Frost.
  • Defence Mechanism Superpower: Killer Frost comes out when Caitlin is scared or angry.
  • Defrosting Ice Queen: She takes longer to come around than Caitlin, but eventually does.
  • Didn't Think This Through: In Season 7 episode "Growing Pains", Frost just going to a bar when there is a warrant out for her arrest was bound to cause trouble.
  • The Dragon: She briefly becomes Savitar's henchman in Season 3.
  • Drunk on the Dark Side: Killer Frost loves using her powers to cause trouble.
  • Easily Forgiven: After spending the tail end of Season 3 working with an evil time traveler and trying to kill most of her loved ones, it's surprising that in Season 4, she's immediately forgiven by everyone without really apologizing. Killer Frost herself even lampshades this, expressing surprise that she kidnaps and stabs them and they still forgive her.
  • Eating the Eye Candy: She openly takes in Blaine's body, when he tantalizingly strips off his damaged shirt in front of her.
  • Elemental Eye Colors: When Killer Frost is in control, her eyes turn blue with a glimmer of white.
  • Elemental Hair Colors: When Caitlin becomes Killer Frost, her hair changes from brunette to white.
  • Emotional Powers: As of season 4, Killer Frost emerges when Caitlin is scared or angry.
  • Everyone Has Standards: When Nazis crash Barry and Iris' wedding during Crisis on Earth-X, she willingly fights and kills the invaders with a massive ice blade.
  • Evil Feels Good: She expresses that she gets a kick or a high out of doing bad things and causing harm to others. This changes when she pulls a Heel–Face Turn in Season 4.
  • Evil Is Deathly Cold: She has cold and ice powers. In addition, she is ruthless, cunning, and lacks empathy. Come Season 4 and she manages to tone down the ruthless and "evil" part of her alter ego.
  • Eye Color Change: Her eyes change from brown to blue.
  • Face of an Angel, Mind of a Demon: Killer Frost is very beautiful and looks almost angelic in physical appearance due to having a combo of Mystical White Hair, Icy Blue Eyes and pale skin. But she was a ruthless villain with not so good intentions and was The Dragon for the Big Bad Savitar in Season 3. She does become more heroic in Season 4 after doing a Heel–Face Turn.
  • Fire/Ice Duo: In the Crisis on Earth-X Crisis Crossover, Mick Rory ends up striking this partnership with her, having the ice meta substitute for his late partner, Leonard Snart. They team up once again in Crisis on Infinite Earths (2019).
  • Foil: (Killer) Frost is one to Firestorm. In addition to the obvious elemental differences, Firestorm is a being composed of two physical individuals fused together, while Killer Frost is the result of two consciousnesses Sharing a Body, who eventually split apart into two.
  • Glass Cannon: Killer Frost is very powerful, but she has her weaknesses. One hit from Vibe against a car and she is knocked out cold.
  • Glowing Eyes of Doom: Caitlin's brown eyes turn blue when she becomes Killer Frost. And when Killer Frost gets angry or uses her powers, her eyes start to glow white.
  • Good Costume Switch: In Season 4, after Caitlin rejoins the team and Killer Frost becomes more of an Anti-Hero, she wears a light blue jacket most of the time as Frost, as opposed to her dark blue outfit of Season 3.
  • Good Thing You Can Heal: She has a built-in Healing Factor. When Caitlin is about to die from an injury, Julian removes Caitlin's Power Limiter to activate her meta-powers.
  • Heel–Face Turn: By Season Four, Killer Frost is no longer a straight up villain, instead becoming more of an Anti-Hero who is willing to help Team Flash if necessary.
  • Heroic Sacrifice: In Season 7, when Frost is arrested and tried for her past crimes, the prosecution calls for her to be given the metahuman cure in order to ensure that she can never again pose a threat. Knowing this will establish a legal precedent that allows the courts to depower metas against their will, Frost requests — and receives — life in prison without parole instead.
  • Hero with an F in Good: Frost's early attempts at legitimate heroism yield mixed results, but she improves over time.
  • An Ice Person: In Season 3. While not fully explained yet, her powers seem to be based on Energy Absorption, which Caitlin demonstrated to her mother by absorbing the energy of a 2000°C heated piece of tungsten.
  • Icy Blue Eyes: Her eyes change to an icy blue color compared to Caitlin's brown.
  • If You're So Evil, Eat This Kitten!: Barry dares her to kill him as that's what villains do. She can't.
  • Ironic Name: As several characters have pointed out, for someone named Killer Frost she's never actually done any premeditated killing before.
  • Jekyll & Hyde: For all intents and purposes, she and Caitlin are essentially two separate characters (who share the same memories) sharing the same body.
  • Jumping Off the Slippery Slope: Her first stint was caused by this, as Caitlin's desperation for a cure pushed her into darker and darker territory. It leads to an all-out fight between her, Barry and Cisco, and it takes Barry goading her to kill him to make her come to her senses.
  • Kiss of Death: A kiss that will cause hypothermia to her victim.
  • Kicking Ass in All Her Finery: Killer Frost often dresses to impress and she manages to be powerful at the same time.
  • Knight in Sour Armor: After becoming a hero.
  • Literal Split Personality: Much to Cisco's shock, Caitlin and Frost are seen split apart in two different bodies at the end of "Central City Strong".
  • Loss of Identity: The more she uses her ice powers, the more she becomes Killer Frost. This is undone at the end of season 3 where the two begin to reach a compromise.
  • Martial Medic: She is primarily a fighter, and will usually switch to Caitlin for The Medic role, but in the heat of combat she can and will perform quick procedures to help her injured comrades.
  • Meaningful Rename: In Season 6, she decides to only go by Frost, since she is not an actual killer.
  • Mini Dress Of Power: Her original costume has one, unlike her Earth-2 counterpart who wears leather trousers, and she turns out to be more powerful than her.
  • Mundane Utility: She uses her powers in the Christmas episode to turn the rain into snow so everyone can enjoy a white Christmas.
  • Ms. Fanservice: Much more than Caitlin, although she had more of those moments on Season 3.
  • Mystical White Hair: Her hair is as white as... well, snow.
  • Never Had a Birthday Party: She laments that in the 30 years she and Caitlin have been born, she never had her own party. Naturally, Team Flash throws her one.
  • Non-Indicative Name: She calls herself Killer Frost but hasn't successfully killed anyone. Except possibly some Nazi Mooks in Crisis on Earth-X, which they almost certainly had coming. Also Black Flash, but he was technically already dead.
  • "Not So Different" Remark: Both Hunter and Savitar invoke this, claiming they and Killer Frost are similar to make her stay by their side.
  • Pay Evil unto Evil: She destroys Black Flash which, while it was meant to destroy any speedster aberrations (like Thawne and the then-paradoxical Savitar), it originally being Hunter Zolomon, a man who kidnapped and tormented Caitlin softens the blow.
  • Power Echoes: Her voice is accompanied by an echo filter, which disappears in season 6 when she begins to appear more often.
  • Power Dyes Your Hair: It changes from brown to silvery white.
  • Power Makes Your Hair Grow: Her hair becomes much longer in length in addition to changing to silvery white.
  • Power Stereotype Flip: Instead of being composed, cool, and collected as most people associated with the ice element are, she is bold, temperamental, violent, unpredictable and impulsive.
  • "The Reason You Suck" Speech: Throws out several of them towards Barry and Cisco when she's irate enough.
  • Red Oni, Blue Oni: Ironically, despite having ice powers, she is the Red to Caitlin's Blue.
  • Required Secondary Powers: She possesses a Healing Factor to offset "cold tissue destruction" that result from her ice powers.
  • Rogues' Gallery Transplant: Killer Frost is a Firestorm villain and usually his Arch-Nemesis.
  • Signature Move: She fires ice blasts with both hands.
  • Ship Tease: Like Caitlin, she and Ralph have shown a lot of attraction to one another.
  • Split Personality: By Season 4, Killer Frost manifests herself as an alter. Caitlin attempts to struggle against her for control before coming to understand her better. Season 6 has Caitlin let Frost be the host most of the time, so she can live her own life for a change.
  • Sugar-and-Ice Personality: She has more ice than sugar compared to Caitlin.
  • Superior Successor: Ultimately, she has a much more variety of tricks on using her powers compared to her late Earth-2 counterpart.
  • Superpowered Evil Side: She begins as Caitlin's, a manifestation of her repressed anger fueled by her ice powers becoming a separate entity. Though by Season 4, she's turned out to be less "evil" and more "snarky".
  • Took a Level in Badass: Her power eventually go beyond ice blasts, such as being able to create ice trails in the air and slide along them to simulate flight and even outpace The Flash. Her ice powers eventually grow so strong that she is easily able to freeze and shatter Black Flash.
  • Took a Level in Kindness: She becomes much nicer as the series goes on.
  • True Blue Femininity: She wears a blue Badass Longcoat (replaced later by a turquoise jacket) coupled with blue lipstick and eyelashes.
  • Villain Has a Point: Killer Frost lays out and blames Barry for all the failures and bad things he did, like letting Ronnie and Eddie die, and possibly being responsible for Dante's death and her developing powers after causing Flashpoint. Ironically, it later turns out to be subverted on the last part — later seasons reveal that Caitlin has had her abilities since childhood and they had lain dormant until the events of the show, where her subsequent Trauma Conga Line caused them to reawaken. Barry had nothing to do with what happened to her, as she was going to become Killer Frost with or without Flashpoint.
  • Weak to Fire: Her weakness is too much heat or overexposure to heat. In 4x15, she was unable to cool down the bomb because of how hot it was. She started to overheat physically to the point where she couldn't use her powers effectively and became weaker.
  • What the Hell, Hero?: When she fully emerges, she calls Barry out on his mistakes.
  • White Hair, Black Heart: Subverted. She was The Dragon to Savitar in Season 3, but does a Heel–Face Turn in Season 4 and joins Team Flash for good.
  • You Are Better Than You Think You Are: It goes both ways. Caitlin says that Frost has the potential to do good despite her reservations and Frost tells Caitlin that she's perfect the way she is despite her feeling inadequate as a person.


Species: Unknown

Played By: Danielle Panabaker

First Appearance Wednesday Ever After (The Flash 9X1)

Appearances:' The Flash''

A being born after Caitlin's experiment to bring Frost back to life goes wrong. She is neither Caitlin nor Frost, and neither human nor meta-human. It is later revealed she is a goddess, in the most literal sense of the word.
    Tropes involving Khione 
  • 11th-Hour Ranger: She is introduced in the final season as Team Flash's newest heroic ally.
  • Ambiguously Human: Chester's experiments reveal she is neither human nor meta-human. It's later revealed she is in fact a God in Human Form.
  • God in Human Form: It's heavily alluded she might just be the goddess Khione in Caitlin's form.
  • Green Thumb: She is able to make plants grow wherever she wishes, including the inside of the human body.
  • Energy Absorption: She is able to absorb speedster Lightning and redirect it back, as Zoom finds out the hard way.
  • Innocently Insensitive: Not really insensitive; she's almost as innocent as a newborn baby, meaning she has no filter. That said while she may sometimes overstep, her words are always stated in kindness.
  • New Powers as the Plot Demands: By her own admission, she discovers new abilities she possesses everyday.
  • Nice Girl: As pure and sweet as newly fallen snow.
  • Physical God: She is a goddess in the most literal way possible, being the personification of nature and has influence over the entire world. She is comparable to the Speed Force, but even more powerful.
  • Power Dyes Your Hair: While Frost turned Caitlin's hair white, Khione's hair has blue streaks.
  • Ship Tease: With Mark, she kisses him and he awakens from his coma.
  • Story-Breaker Power: She is hands down the most powerful member of Team Flash, and quite possibly the most powerful hero in the entire Arrowverse (possibly only equaled by the Spectre). She is a powerful nature-based Reality Warper who discovers new powers everyday and seemingly has no limit to what she can do.