The Suicide Squadis a name for two fictional organizations in DC Comics Universe. The first version debuted in The Brave and the Bold#25 (1959), the second, also known as Task Force X, in Legends#3 (1986). An "original" Suicide Squad was retconned into continuity in Secret Originsvol. 2, #14 in order to form a connection between the first Squad and the second.

The first Suicide Squad was a minor backup series about a quartet of non-powered adventurers fighting super-powered opponents that appeared in The Brave and the Bold#25-27 and 37-39. The Squad consisted of Rick Flag, his girlfriend Karin Grace, Dr. Hugh Evans, and Jess Bright. This team was created by Robert Kanigher and Ross Andru. Later continuity, in Secret Origins Annual#1, established that the team, in its earliest incarnation, was expressly formed to fight monstrous menaces as a replacement for the Justice Society of America, whose members had mostly retired in the wake of unjust accusations during the McCarthy Era.The Suicide Squad was revived in the mini-series Legends, and were created by John Ostrander. The renewed concept involved the government employing a group of supervillains to perform missions that were almost certainly suicide runs, a concept popular enough for an ongoing series titled simply Suicide Squad. They were often paired together with the government agency related series Checkmate, culminating in the "Janus Directive" crossover.The concept self-consciously emulated the World War II film The Dirty Dozenand the television series Mission: Impossible.[citation needed]In addition, the existence of the squad was top secret, creating much tension within the group and leading the group to be targeted (unsuccessfully) by the likes of Lois Lane and Batman (who was forced to back off from investigating the group when Amanda Waller threatened to use the government's resources to expose Batman's secret identity). While some of the Squad members, such as Bronze Tiger, Deadshot and Captain Boomerang were permanent fixtures, the balance of membership was made up by a rotating cast of, often very minor league, villains. These villains would agree to take on Suicide Squad missions in exchange for early release from prison. Thus, the existence of the squad served as a partial explanation for how villains who had been previously defeated by a hero would end up free again a few issues later. While the team were successful on most of their missions, there were often failures (most notably the capture of Nemesis by Russian forces after a failed mission in Russia) or the death of one or more members. The use of minor villains and heroes added to the jeopardy, as it was not clear whether any given character would survive a mission, and the series did not shy away from killing off some of its principal characters, most notably Rick Flag, Jr., who was killed at the end of the book's second year. The series was also notable at the time for examining the lives, motivations and psychological makeup of its characters with one issue per year featuring the group's psychologist interviewing each member.The Suicide Squad lasted 66 issues, going on to appear in several guest appearances in titles like Superboy(a Hawaii-based version, incorporating many of Superboy's enemies, as well as Superboy himself) and Chaseafter cancellation.The second Suicide Squad volume was published in 2001 by Keith Giffen and Paco Medina. Though the group's first issue featured members of Giffen's "Injustice League" group as the Suicide Squad's membership, the roster was promptly slaughtered save for Major Disaster and Multi-Man (whose powers make him unkillable). The two departed after their one and only mission, leading Sgt. Rock to recruit new members, most of which died in the missions they went on.

Checkmateis a fictional covert operations agency within the DC Comics universe. It first appeared in Action Comics#598 and proceeded to have its own ongoing title in Checkmate!(vol. 1). In the wake of events depicted in the mini-series The OMAC Projectand Infinite Crisis, Checkmate has been re-chartered as a United Nations Security Council-affiliated agency and has its own new series, Checkmate(vol. 2).

The Checkmate organization was created by Paul Kupperberg and Steve Erwin, first appearing in Action Comics#598 in 1988. The precursor to this fictional organization was known as the Agency, first appearing in Vigilante#36. Harry Stein was appointed Valentina Vostok's replacement in The Agency's command position by Amanda Waller. Stein later sought out the most stable personnel available from the American and international intelligence and law enforcement communities to form Checkmate. His agency would field only the best-trained and well-equipped of agents, working under the strictest rules of secrecy. For the organizational structure of the re-organized Agency, Stein chose the game of chess as his working model.[2]Stein brought in Gary Washington (Knight One) and Black Thorn as Checkmate operatives, both of whom were his friends, and both of whom were introduced during his run on Vigilante.Checkmate!was at various times involved with the other government agencies in the DC Comics universe, primarily the Suicide Squad, which resulted in the crossover "The Janus Directive". Checkmate!was canceled after 33 issues but the organization continued to appear, mostly in titles related to either the government or Batman.After the events of the mini-series The OMAC Project, a precursor to the Infinite Crisislimited series, the Checkmate organization was re-organized and its title was revived with Checkmate(vol. 2). This volume is scheduled to end after publication of its 31st issue dated December 2008.[3]After the cancellation of the second volume, the team return in the Final Crisis one-shot tie-in "Resist" by Greg Rucka and Eric Trautmann.