Raised by an abusive father, Len Snart sought to start a criminal career following the death of his grandfather. At first, he attempted simple thievery with a band of thugs. After this failed to produce satisfactory results, he went solo. During a botched robbery of a cyclotron, Snart's gun was altered by the cyclotron's radiation, allowing it fire beams of pure cold, and from time to time, cast illusions. Putting togther a blue and white parka, Len became Captain Cold, one of the Flash's deadlist enemies. He is currently the leader of the Rogue's Gallery. But in the New 52, after the Crime Syndicate was defeated, Cold stopped his life of crime and became a member of the Justice League along with Lex Luthor.
Powers and Abilities
Captain Cold wields special "cold-guns" which he uses to freeze anything and everything to the core. It can even turn the moisture contained in thin air into solid ice. In the New 52, at one point after going through experiments, he gained the ability to uses these powers himself to where he could created a special freezing field to reduce the Flash's speed to human level. These powers were later removed by Deathstorm during the Forever Evil event, forcing Cold to go back to using his cold-guns.
Justice League Unlimited
He appears in the show Justice League Unlimited in the episode "Flash and Substance" where he conspires with his fellow rouges about killing the Flash. They all do bad until he decides that they should all attack him at a museum. Later they all attack Batman, Flash, and Orion. During the fight he and Captain Boomerang severely hurt and nearly kill Orion but he escapes. Eventually one of his beams ricochets onto him, freezing him and is later taken to jail. In this show he is voiced by Lex Lang.
Batman: The Brave and the Bold
He later appears in the show Batman the Brave and the Bold in the episode "Requiem for the Scarlet Speedster" where in the Flash's absence commits crimes with his fellow rouges. They then fight Batman, Kid Flash and the original Flash. In the fight he accidentally freezes Heat Wave and is defeated by the original Flash. In this show he is voiced by Steve Blum.
In the show Young Justice, Cold appeared in the episode "Independence Day" where he robs a jewelry store but is stopped by Flash and Kid Flash. He later appears in the episode "Terrors" where it is revealed that he let himself be captured to help the other ice villains in an escape attempt in Belle Reve prison which is where he is sent to. In the episode "Coldhearted" he powers an ice weather machine along with the other ice villains and later made a cameo in his prison cell. In the episode "Satisfaction" he uses a big freeze gun to freeze a bank and starts to dig it up but is attacked by Zatanna, Rocket, Batgirl, Miss Martian, Black Canary, Bumblebee, and Wonder Girl. In this show he is voiced by Alan Tudyk.
Superman/Batman Public Enemies
In the animated movie Superman/Batman Public Enemies once again helping his fellow ice villains take down Batman and Superman and collect the bounty on them. In this movie he is voiced by Michael Gough.
In the live action show Smallville, Cold appears in the episode "Prophecy" working for Toyman. He sends him to kill Inpulse.
Wentworth Miller portrays Leonard Snart in the 2014 TV series The Flash and DC's Legends of Tomorrow coming in 2016. In the episode 'Going Rogue', he is first seen hijacking a truck, but his plan is stopped by The Flash. He is later seen with a person selling him some guns, one of which he keeps for Heat Wave. He takes a gun that can fire cold flames and kills the seller. He goes to a museum and attempts to steal a gem, but The Flash shows up. He tests his gun by shooting at people, however he only killed one.