Quadrant

"They are very real. They control all criminal enterprises across the country. Four Corners. They did not get this type of power without patience..."

- Diaz speaks about the Quadrant

The Quadrant is a villainous organization in the sixth season of the series Arrow.

History
The Quadrant is an extremely powerful criminal organization which controls the criminal underworld in all four corners of America - hence the name.

After corrupting the officials of Starling City and impeaching mayor Oliver Queen, crime lord Ricardo Diaz heads to Blüdhaven to meet with the Quadrant, hoping to be introduced into the syndicate. Diaz reveals to a leader that Star City belongs completely to him and that both officials and infrastructure are under his control. He states that he will allow the Quadrant to conduct business in the city and will not even charge them for it, in exchange for a seat at the table of the Quadrant. This amuses the man, who claims that the Quadrant is not a small gang which always has room for people who have something to add. He claims that the Quadrant is like a family and is not welcoming to outsiders before they can know these Outsiders operate on their level. The man then makes Diaz an offer - if he can find out the location of one of their men, Bailor,  who has captured by the FBI, the Quadrant will agree to Diaz' terms.

After Diaz returns with information on Bailor's whereabouts, Cartier then orders Diaz to fetch the man for the Quadrant, as a favor among future business partners. Although Diaz agrees, Cartier has both Bailor and Diaz shot after they escape the FBI safehouse. Cartier then calls his father, whom he tells that the deed is done, and Cartier sr. decides to send some men to Star City to take over Diaz' assets and make the city theirs. However, Diaz survives and storms Cartier's nightclub where he interrogates and tortures him until Cartier reveals that he and his father wanted to take over Diaz' city and never even relayed his proposal to the Quadrant in the first place.

To enter the Quadrant nonetheless, Diaz drives up to their headquarter, the Villa Centanni, where he and Laurel kill several henchmne, Cartier included, and storm the business meeting of the Quadrant. Once more, Diaz proposes the Quadrant billions of annual income if they make business in Starling City, demanding nothing but a seat at the table. Although Cartier sr. refuses, he is simply shot by Diaz and the other leaders, intrigued by Diaz' proposal, accept and allow Diaz to join them.