Richard Flagg, Sr. was a veteran World War II air pilot, and was friends with Kyle "Ace" Morgan, Martin Jordan, and King Faraday. During 1944, Flagg lost his entire squadron through the course of the Pacific theatre and becoming the only survivor. His survival and continuing struggle throughout the war made him stripped away of his humanity and caught the notice of the O.S.S., who assigned him in leading a squad of convicts and insubordinates. As the O.S.S. saw the notion that men with nothing to lose would make perfect candidates for missions with very low odds of survival. Thus the creation of the so-called "Suicide Squad". Over the years Flagg led wave after wave of broken men to their graves in the name of freedom, which in turn made him felt sorrowfully responsible for their lives wasted.
Near the end of the war, Flagg was escorting German scientist Dieter Teschner undetected through the Pacific for his contribution for America's post-war plans. However, the plane carrying them crashed landed on Dinosaur Island, where he and his men attempted to survive against the island's prehistoric inhabitants. Flagg was left as the only survivor. While planting some traps, he witnessed Sarge of the Losers being killed by a T-rex and returned to his cave hideout and meet with the remaining Losers, Johnny Cloud and Pooch. Flagg was able to obtain Teschner's scientific notes on microfilm and traversed with Cloud and Pooch to a awaiting seaplane to escape the island. However, once on the beach Flagg learns from Cloud that he intends to stay behind and kill the T-rex that killed two of his comrades. Flagg was against it and refuse to see him throw his life away for vengeance. But Cloud force him to leave at gunpoint before Flagg bid his luck and farewell to Cloud in which he died in accomplishing his mission in avenging the Losers.
By the 1950s, Flagg led the Suicide Squad's successor, Task Force X. He and his new team consisting of Karin Grace, Hugh Evans, and Jess Bright whose purpose was to "react creatively to any challenge, Terran or Alien, scientific or biologic" in the midst of the Cold War. Also, Flagg's marriage life didn't lasted well which ended with divorce, forcing him to never meeting his ex-wife or seeing his son, Richard Flagg, Jr., for his entire later life. Flagg and Task Force X later became involved in America's first secret spaceflight to Mars, Operation Flying Cloud, which was named after Johnny Cloud that Flagg had strongly insisted on naming it in honor of the last Loser. Under the project, Flagg met Martin Jordan's son Hal Jordan, who signed on the project recommended by Ace Morgan. Throughout the trainings, Flagg and Jordan didn't get along too well and ultimately leading the latter to be booted off of the program for his showboating attitude, which could have jeopardize the entire operation and the crew's lives.
Once Flying Cloud was launched, Flagg and Karin Grace faced dire peril as Jess Bright panicked on the flight and sabotaged the rocket. Knowing that their survival is dim, Flagg made a personal transmission to Hal, revealing that since Martin Jordan's death, he and the other airmen decided to watch over his son's safety in times of conflict. In which Flagg personally knows that having Hal on the mission and combining with Flagg's survival odds would doom Hal. Also for the fact that the entire operation had the rocket carrying weapons of mass destruction that would be use if Mars's inhabitants are a threat, and should rocket were to be destroy in its entry to Earth's atmosphere it would release the weapons and expose its destruction over the planet. Knowing what has to be done, Flagg and Karin together detonated the rocket and killing themselves. Before their timely deaths, Flagg was in a new relationship with Karin.
Both Flagg and Grace were posthumously given a funeral at Arlington Cemetery and were given a 21 gun salute as per recommended by President Ike Eisenhower.
- In the animated adaption of Justice League: The New Frontier Rick Flag (sans "Flagg") was voiced by Lex Lang. A younger Rick Flag Jr. makes a cameo in the end of the movie.
- 5 Appearances of Richard Flagg, Sr. (Earth-21)
- 4 Images featuring Richard Flagg, Sr. (Earth-21)
- Quotations by or about Richard Flagg, Sr. (Earth-21)
- Character Gallery: Richard Flagg, Sr. (Earth-21)