Doctor Doom is a freelance spy-master.
The good doctor (as opposed to the far more famous evil villain who would come around 25 years later to harass the Fantastic Four) is the leader of a small group of highly loyal and trained operatives, hiring their services out to nations around the world.
The man in charge is never addressed, as far as we can find, by his first name so we only known him as Doctor or by his last name. We also do not know very much about him although we can surmise a fair amount.
He and his group operate out of the United States and his makes his home there, lending credence to the fact that he is American. The fact that his son is enrolled in a private boarding school in the States adds to that theory but it does remain just a theory.
Doom is likely in his early forties since the images depicting him in the comic record of his adventure clearly show a not-young and not-old man.
The fact that Doom has a son who is close to 10 years of age show us that he started a family later than average and since he is at the time of the first recorded adventure already quite established makes us certain his earlier years were spent plying his espionage skills and building up his business.
It was during those earlier days that he also made a lasting enemy of the foreign spy, also head of his own organization, called the Falcon. This Falcon is supposedly quite feared by many but still not ferocious enough to be immune to deadly threats by his clients.
Helping Doom in his missions are at least 3 operatives: the beautiful and highly resourceful Sonia (no last name given), the dangerous and capable Mark Cameron (also sweetheart of Sonia), and Roark (about whom nothing is known). Also working for the Doctor is his close friend and aide, Igor, a brooding hulk of a man who does not like people messing with his Master.
Doom is rather easy to recognize with his slick back dark hair and Vandyke beard which is pointed on both sides of his jaw and comes to a sharp point at the tip. He is prone to stroking this beard while he contemplates his next moves.