Dr. Doug Robert was a doctor and a member of the Impossible Missions Force.
Doug had great confidence in his own skills and his professional ethics.
He became the only field agent ever to win an argument with Jim Jim Phelps (Peter Graves). In the episode "The Rebel", Jim had sustained a severe bullet wound in one arm. Doug refused to let it go untreated, despite Jim's insistence that other things took precedence. In the end, Jim sat down and let Doug work, receiving only a glare in return when he urged the physician to hurry it up.
Even in his short on-screen time with the IMF, for unknown reasons, Doug repeatedly used aliases with the surname "Lang."
Jim would call upon Doug for missions that required administering medical treatment to field agents or safely incapacitating targets. In Doug's final appearance, "Encore," Doug anesthetized elderly mobster Thomas Kroll (William Shatner) and administered hormones and a mask (applied with paraffin wax) to trick Kroll into believing he was more than 30 years younger than he actually was.