One Year Later following the events of the Infinite Crisis:
The organization is approved and sanctioned by the UN to monitor metahuman activity. As always, the organization is divided into two teams: The White team that handles intelligence and the Black team that handles operations. The members of the organization are designated with positions similar to that of chess pieces. The King and Queen are the leaders, Bishops their advisors, Knights their field leaders and Pawns their foot soldiers. To further balance the organization, a "Rule of Two" has been implemented requiring every super-powered member to have a non-powered member in the same position. For instance the current White Queen Amanda Waller is checked by the White King, Mr. Terrific and vice versa. This rule goes down the ranks up until Pawn.
The covert action group code name Checkmate was created from the ashes of its preceding group, the Agency, which was originally set-up by Amanda Waller to serve as a small quasi-independent branch of Task Force X under the command of Colonel Valentina Vostok to perform operations worldwide considered vital to the security of American interest. While the Agency utilize mostly plainclothes operatives, Vigilante II and Peacemaker.
After the relaunch of 2011, Checkmate was mentioned by Amanda Waller which means Checkmate is still active.
Smallville (TV Series; 2001 - 2011)
The Checkmate agency appeared in the ninth season of the TV series "Smallville". It was run by the White Queen Amanda Waller. Checkmate first showed up to hunt the Justice Society Of America down. All members of the JSA were arrested and later the JSA was disband. Years later, Amanda hired Icicle to tracking down and killing the last members of the JSA. After Cameron killed Star-Spangled Kid and Wesley Dodds, he killed Doctor Fate (Kent Nelson) and took the helmet of Nabu for himself. Icicle was stopped by the Justice League of America. After this, Icicle returned to Checkmate and Amanda pointed a gun on him. She only said "Welcome to the Suicide Squad!" and fired the gun.
Later, Checkmate tried to get the true identities of every JLA member, they kidnapped their Watchtower (aka Chloe Sullivan) but she was saved by Superman. After some events, the Castle was burned down by General Zod and most of the Agents died. The fate of Amanda Waller is unknown and never revealed - also the fate of her White Knight Stuart Campbell is unknown. It's likely both died in the fire.
The known members of the Smallville-Version of Checkmate are: Amanda Waller (White Queen; unknown), Tess Mercer (White Knight; deceased), Stuart Campbell (White Knight; unknown), Edward Lott (White Rook; deceased), Paul Brenner (White Rook; alive), Lois Lane (White Pawn; retired), Maxwell Lord (Black King; presumed alive), Ray Sacks (Black Knight; alive), Icicle (Black Pawn; presumed alive). Checkmate was related to the Suicide Squad