Despite being a supervillain, Cold has his own moral code. He also only kills for two reasons: when it is a kill or be killed situation or when he is out for revenge.

Leonard Snart grew up in a "trailer trash" home outside of central city. His father was a drunken ex-cop who beat his wife and two children. Snart's mother often left his father due to the beatings but always came back.

As a child, the only good influence in Snart and his sister Lisa's life was their grandfather, who was an ice deliveryman. He would take the children with him to restaurants, ball parks, etc and give them ice cream.

Snart's grandfather died before he turned twelve. At that point, he and his sister had learned to never cry, to be emotionally cold.

Eventually, Snart left home. Lisa wanted to go with him but he told her to stay since she was a talented ice skater and he didn't want to ruin her chance to be a professional skater or let her get involved with the kind of people he planned to work for.

Snart worked with a small gang of thieves that had designed special glasses to protect their eyes from gunflares. While breaking into a building to rob it, the gang was captured by Barry Allen, the Flash. Snart swore revenge.

In prison, Snart studied kinetic energy and thermal motion, realizing that absolute zero temperature would stop even the Flash.

When finally got out on parole, he broke into a lab and stole blueprints and a cyclotron to power his new weapon: the cold gun.

Taking the glasses from his former gang, he changed his name to Cold, adding the title "Captain" to give the illusion of authority.

He battled the Flash throughout the silver age, often teaming up with other Rogues especially Captain Boomerang, the Trickster, the original Mirror Master and his own sister: the Golden Glider.

After Barry Allen died in the Crisis on Infinite Earths, Captain Cold reformed. (This was later retconned as the work of the Top, who hypnotized several Rogues into reforming. The Top's own mind had been alterned by Zatanna.) He and his sister opened up a bounty hunter business, occationally working with the new Flash, Wally West.

During the events of Underworld Unleashed, Cold was one of the Rogues that was tricked into selling his soul to Neron. He was saved by the Flash.

By this time, Lisa had stopped working with Cold. Instead, she took on a series of partners, usually large and stupid. She outfitted them with her brother's weaponry, naming them "Chillbane" and finding a new partner for each one that was arrested.

Eventually, she came across a smarter Chillbane who realized that he was being used. He killed Lisa and then faked his own death. Years later, Cold would hunt Chillbane down and kill him. Instead of celebrating his victory, he turned away his usual hooker and spent the night alone. He shead his first tears since he was twelve, thinking to himself "As much as I hate it, my heart's not always cold."

After Blacksmith's Network was disbanned, Cold decided to reform the Rogues. He teamed up with the new Mirror Master, the Weather Wizard and the new Trickster. He enforced a strict "no drug" policy, beating Mirror Master severly when he broke it, telling him "If you want to make your nose bleed, we can do it the old fasioned way." Cold also lowered the Trickster's pay by 90% for tieing bombs to stray dogs.

During Identity Crisis, Cold and the other Rogues were robbing a bank when they were informed by Mirror Master of the death of Sue Dibny. Cold walked out of the vault, telling Mirror Master to send Mr. Dibny flowers with no card. When Weather Wizard protested leaving in the middle of a job, Cold said that he had lost the stomach for it.

Shortly after, Captain Boomerang died and the Rogues took his son, Owen Mercer, in, allowing him to become the new Captain Boomerang. At the time, Cold believed that Owen might have been his nephew (as his father had dated Lisa) though it was later revealed that he was actually the son of Meloni Thawne.

Cold lead the Rogues during the Rogue War. He battled Heatwave, eventually bringing him out of the Top's mind control and convincing him to join the Rogues. When he learned that the Top had been responsible for the reformed Rogues' behavior, Cold froze him with his cold gun and shattered him. Cold explained that the Top had broken the rules and that Rogues shouldn't fight each other. Afterwards, he consoled Captain Boomerang, telling him that the Rogues were his new family and that nothing was more important than family...except maybe revenge.

After the Rogue War, he and the rest of the Rogues (with the new Trickster being replaced by the old Trickster, who had also been freed from the Top's mind control) joined Luthor's Society. During a battle against the Outsiders, the Rogues left Owen behind and he and Cold are no longer on speaking terms.

One Year Later, Cold is one of the Rogues that, following Inertia's plan, manages to sever the Flash's tie to the speed force. Upon realizing that this was not the Flash they knew, the Rogues considered letting Bart go. Bart insisted that he was the Flash and broke free, intending to kill Inertia. The Rogues caught him and Cold, along with Weather Wizard and Heatwave delivered the killing blast to the Flash.