Dr. Daniel David Briggs, Ph.D., was a veteran of the United States Army's G-2 (Intelligence) section who had been honorably discharged with the grade of lieutenant colonel, and, during his Army service, the former Commanding Officer of a wartime unit, unofficiallly known as "Briggs's Squad," that performed complex missions for the United States armed forces. The team's other personnel were Barnard "Barney" Collier, William "Willy" Armitage, Rollin Hand, and several others who failed to make it into the TV series afterward. After the war, Briggs rounded up members of his former team (some of whose personnel were believed to have turned to crime) and pulled them together to perform missions for the US Government. This new team became an independent covert-operations agency and was renamed the Impossible Mission Force, "IMF" for short, and Briggs was named as both its founding Director and the team captain of the mission team called "The Director's Own," for at least one year.
(The pilot of Mission: Impossible had the voice giving him his mission stating, "I hope it's 'welcome back,' Dan. It's been a while." Plus, other characters in the first season referred to past exploits in which Briggs had involved them that predated the TV series, indicating that the IMF had been active for sometime before the "Pilot" both with, and without, Briggs in the leadership role.)
Briggs, as stated above, had been a lieutenant colonel in the United States Army, presumably at the time of the Korean War, and he had earned a Ph.D. in analytical psychology; indeed, he was a well-paid behavioral analyst outside his government service. (This made him an expert in human beings and hence a top-notch "guesser.") It is commonly believed that he and James Phelps were two of the founders of the IMF.
While Briggs had his choice of many different agents for his missions, he usually picked a specific group consisting of actor and theater-arts teacher Rollin Hand, fashion model and actress Cinnamon Carter, electronics company president and electronic engineer Barnard "Barney" Collier, and bodybuilder, heavy laborer and mechanical engineer William "Willy" Armitage. It was this team, the IMF's all-time most successful (especially after James Phelps became IMF Director), that pioneered the employment of grand-scale confidence games as the IMF's chief method of accomplishing missions.
His primary role was as the mastermind behind the operation, but when a job required it he could act as a supporting character.
The exact fate of Dan Briggs is a mystery. Presumably, whatever caused him to take his original leave from the team drove him back into inactivity as well, turning the leadership of the IMF over to Jim Phelps, who was, perhaps, in charge of the IMF during Briggs's initial absence as well.
- Actor Steven Hill lost his role as Briggs partially because his Orthodox Judaism conflicted with the shooting schedules. He subsequently went on to act out the role of New York County District Attorney Adam Schiff in Law & Order.
- Mission: Impossible (1966) - Season 1