Leonard Snart (Earth-1)

History
Leonard Snart is a criminal known as Captain Cold. Over the course of his criminal career, he's had many run-ins with The Flash, and even attempted to killing him on multiple occasions. Somehow over the years, he learnt of The Flash's secret identity, Barry Allen.

One day, Snart intruded Barry's home in need of his assistance. Snart claimed that his sister, Lisa Snart, had been killed by a man with a sword, whom Snart had failed to pay money back to. He asked the Flash for his help, and he agreed. The two went to the scene of the supposed murder, Warehouse 17, only for the Flash to learn that it was a trap. Snart used his cold-gun to freeze the Flash. This was to keep him in Flash long enough for Snart to activate a device that would freeze all of Central City. Joe West managed to find The Flash and free him, just in time to stop Snart from activating the device. Following this, Snart would be sent to Iron Heights.

It wouldn't take long for Snart to break out of Iron Heights and extract revenge on the Flash. He kidnapped Iris West to set up a trap for the Flash, which he fell into. It seemed as though Cold had the Flash beaten until Vibe showed up and stopped Snart.

Related

 * Appearances of Leonard Snart (Earth-1)