#711 is a superhero from the Golden Age of comics. He was created by George Brenner and published by Quality Comics. #711 first appeared in Police Comics #1 (August 1941) and lasted until #15 (January 1943), when he was killed.
Daniel Dyce was a District Attorney who was almost an exact twin of his friend, Jacob Horn. Jacob was in prison, but wanted to see his wife give birth, so Daniel agreed to become a prisoner while Jacob was with his wife. However, Jacob is killed in a car crash on the way to the hospital, so Daniel was stuck in jail. Daniel was able to tunnel himself free, but instead of escaping, he decided to return to his cell. Each night he uses his tunnel to go outside and fight crime, then returns before the morning. Dyce adopts the name #711, a reference to his prisoner number. Daniels was killed two years later by the mobster Oscar Jones. The hero Destiny sees this take place, and starts his crime fighting career when #711 died, replacing his feature in Police Comics.
Like many early comic book heroes, #711 did not wear a traditional costume but rather was modeled after the traditional pulp magazine heroes. He wore a green cape, a brown business suit, and a wide-brimmed fedora which cast his eyes in shadow. #711's trademark was a calling card made of a mirror with bars painted over it; when an unlucky criminal would look at the card, they would see themselves behind bars.
Following the Golden Age, many of the Quality Comics characters were purchased by DC Comics, while others lapsed into the public domain. DC has used #711 only once in their publications, a Millennium Edition reprint of his first appearance.