Seven Deadly Sins

"Apparently, the Seven Deadly Sins were the strongest and cruelest order of knights in the kingdom, formed by seven brutal criminals who carved symbols of seven beasts into their bodies. Ten years ago, they were accused of plotting to overthrow the kingdom, and disintegrated after all the Holy Kights launched a general offensive against them."

- Elizabeth to Meliodas and Hawk in The Seven Deadly Sins

The Seven Deadly Sins (七つの大罪 Nanatsu no Taizai) were the strongest and cruelest order of knights in the kingdom of Britannia which was formed by seven brutal criminals, who had all been convicted for grievous crimes and had carved the symbols of seven beasts onto their bodies. After having been framed for murdering the Great Holy Knight, they were disbanded, and branded as traitors and villains.

Background
The group, which was originally an order of knights serving the kingdom of Britannia, became branded as traitors and villains due to being framed for assassinating Zaratras, the Great Holy Knight. It is suspected that one of the members in the Seven Deadly Sins could be a traitor who helped plot the trickery. Each of them owns a sacred treasure, which were entrusted to them by King Leoneth when the group was formed; Meliodas, Diane and Ban, however, sold his, lost hers and had his stolen, respectively.

Sins Committed
Each of the Seven Deadly Sins have committed a grievous crime, for which they were sentenced and judged by the kingdom of Britannia, before forming the group.

Meliodas
Meliodas' sin has yet to be revealed. However, it is believed that Meliodas destroyed an entire country that was as powerful as Britannia by himself after losing himself in his wrath.

Diane
Diane's sin has yet to be revealed.

Ban
As the only survivor of the Fairy King's Forest, he took the blame of destroying the the forest, drinking water from the Fountain of Youth and killing its guardian saint upon himself. As a result, he was convicted, sentenced to death, and became known as the Sin of Greed due to his apparent greed for immortality.

King
King's sin has yet to be revealed.

Merlin
Merlin's sin has yet to be revealed.

Escanor
Escanor's sin has yet to be revealed.

Gowther
Gowther's sin has yet to be revealed.