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Quote1 The only way I could feel warm, the only way to melt the ice in my veins... was to kill. Quote2
Killer Frost src

Caitlin Snow is Frost (formerly Killer Frost), a scientist with cryogenic powers. Though she started out as a villain, she has since reformed, and even joined the Justice League of America.


Caitlin Snow was a young and bright scientist working for S.T.A.R. Labs assigned to an underfunded S.T.A.R. Labs Outpost #72 in the Arctic Circle, where the deceased researcher Dr. Louise Lincoln had been working on a Self-Sustaining Thermodynamic Ultraconductor Engine that could subvert the second law of thermodynamics in order to create perpetual motion. Caitlin became interested in continuing Lincoln's work, in spite of her colleagues warning her against it.

When Caitlin succeeded in finishing the S.T.U. engine, her colleagues turned on her and revealing themselves to be working for H.I.V.E., as they were expected to ensure that the engine was never made public in order to protect H.I.V.E.'s investments in the energy industry. Furthermore, they were also responsible for Lincoln's death, and they then proceeded in silencing Caitlin by placing her in the working S.T.U. engine. In a panic, Caitlin ripped out the wires for the engine's coolant system, consequently infusing her biological makeup with ice. As a result, she became a vampiric being who craved for heat, and killed the H.I.V.E. agents.

After carrying out her vengeance, Caitlin continued to search for other sources of heat; she attacked a Norwegian research camp and stole their helicopter to fly to her hometown of Pittsburgh, where she encountered and fought Firestorm. While fighting Firestorm, Caitlin discovered that Firestorm's powers can temporarily heal her condition, and devoted her time to seeking and confronting him. She soon learned about the Firestorm Matrix and attempted to recreate it.[1]

Justice League of America

Killer Frost was captured at some point after, and transported to Belle Reve where she was forced to join the Suicide Squad. After reforming and saving the world from Eclipso, Batman had her released on parole from Belle Reve and she joined the new Justice League of America.[2]

After joining the new Justice League of America, Caitlin found herself often in tense company as few of the team immediately trusted her. Black Canary initially mistook her for a rogue criminal when she and Batman attempted to recruit her, while Lobo remained openly antagonistic towards her, despite his own much greater history of violent supervillainy. Besides Batman, the only teammate who was completely nonjudgemental of her was Ryan Choi, the new Atom, with whom she made an immediate connection with due to their shared scientific expertise, and the two became quick friends.[3]

Caitlin quickly developed romantic feelings for Choi, who reciprocated them, though his inexperience with women and low self esteem caused him to be completely oblivious to Caitlin's attraction to him, while Caitlin was too ashamed of her past and her condition to make her feelings known. Their teammates, though, all picked up on their attraction. Together, the two swore to aid the other in both their respective personal objectives, for Caitlin this was curing her condition, and for Ryan it was locating his lost mentor, Ray Palmer.[4]

During one adventure, when their lives were in danger, Caitlin confessed her feelings to Ryan, who in-turn reciprocated, and the two began a slow and steady relationship, as they were unable to be physically intimate due to Caitlin's condition.[5] As time went on, Caitlin became increasingly agitated by her condition, until the team were attacked by Prometheus, who took each member down systematically. Using Caitlin's condition and her reliance on external heat against her, he tricked her into a room that was below freezing, causing Caitlin's body to begin shutting down. When Ryan and Black Canary managed to free her, she was so drained she couldn't control her heat vampirism, and was forced to drain Afterthought to near death in order to stabilise herself.[6]

This event left Caitlin scared enough of her powers that she ended up agreeing to a bargain with Queen of Fables to cure her condition; however, unable to sacrifice the world for her own sake, she reneges on the deal and helps the Justice League of America defeat her, at the cost of her cure. The experience, however, leads to her re-evaluating her condition, choosing to view it as a chronic condition she needed to manage rather than a disease she needed to cure.[7]

Dark Crisis

On Christmas Eve, Killer Frost was on monitor duty with Firestorm at the Hall of Justice.[8] Following the disappearance of the Justice League, with Black Adam claiming that they were killed by Pariah, Caitlin was recruited by Jon Kent into his new Justice League, which she accepted.[9]

After Deathstroke and his army of supervillains destroyed Titans Academy, Black Adam took control of the new League.[10] However, when he told the League that they would need to kill their enemies in order to be effective, most of them refused. This infighting caused the team to quickly disband.[11]


  • Unique Physiology: Her new state is very basic, almost primal. Her body is completely encased in permafrost. She is not made of ice but she generates organic ice-like cells which make up her changed genetics.[1]
    • Cryokinesis: She can generate ice spikes to spear her opponents, kill an ordinary human with her freezing kiss and/or create a ice storm powerful enough to freeze everything, killing multiple people.[1]
      • Heat Absorption: Frost is a so called "Heat Vampire", to stay alive, she must regularly absorb heat. The most efficient way to satiate this "hunger" is to absorb the body heat of others.[1]
    • Superhuman Durability: Caitlin can survive a shotgun shot to the stomach without serious damage.[12]



  • Power Instability: Frost will die unless she regularly absorbs heat. This extends to areas of extreme cold for too long. This in turn makes her immune to overheating.
  • Allergies: Frost suffers an allergic reaction upon consuming cinnamon. Without an antihistimine, Frost can suffocate due to her throat swelling.[8]



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