Gustav Hauptmann was a scientist working for Adolf Hitler and the Nazi Party for the Third Reich, and left without a powerful leader to follow when the party fell. He later joined the Red Skull, following him religiously until Doctor Doom captured him away to use his expertise for his own ends. Hauptmann was a fanatically loyal servant, accepting every whim of Doom’s, and turning in anyone who would betray him.
When the Fantastic Four traveled to Latveria to investigate Doom’s secret robot army at the behest of Nick Fury, Hauptmann helped Doom design and set loose his newest line of killer robots. Doom initiated a test in which he let two captives appear to defeat him and board a powerful tank before he let one of the robots loose to attack them. The robot soon destroyed the tank and captured the men, and Hauptmann was forced to hide behind Doom’s armor when the fuel tank blew.
Shortly afterwards, he oversaw the sedation and hypnotism of the Fantastic Four, Doom’s prisoners, so that they would be unable to use their powers. Once the Fantastic Four faced the robots and began to fight them back, Hauptmann braved Doom’s wrath to warn him not to underestimate Mister Fantastic’s abilities, as Doom had created a weakness in the robots that Reed might discover. Doom was angry at first, but agreed, and showed him a model of the village the four were trapped in, revealing a pair of nitroglycerine bombs that were built underneath it. Hauptmann, despite his own ruthlessness, was shocked that he would throw away his subjects so easily, but Doom explained that he would tear apart the world to destroy his hated enemies. The Fantastic Four did succeed in beating the robots, and Doom set off his bomb, though Hauptmann reminded him of his subjects’ lives moments before; but too late. However, the Invisible Girl arrived in time to save them all.
The four - then five - quickly made their way to Castle Doom itself and Hauptmann watched as the Thing threw a steeple into the battlements. An artist, paid to paint Doom’s portrait, encouraged Hauptmann that it was an ideal time to abandon Doom to save themselves, but Hauptmann laughed at him and declared that he would turn him in to Doom for punishment. Hauptmann then informed Doom of the heroes’ attack, but Doom was already aware, and scoffed at him showing him the piano he would use as a sound weapon against them.
Later, when Hauptmann discovered that the artist was in fact a S.H.I.E.L.D. spy, he threatened to use a flamethrower to take care of him, despite the art surrounding them, which the artist pleaded for their safety. Before he could fire, however, Reed Richards showed up and stopped him; in order to impress his master, Hauptmann prepared to turn the flamethrower on Reed. But in an ironic twist, Doom turned the sonic weapon he had showed Hauptmann before on his own servant in order to spare his priceless works of art. The weapon focused its ray solely on Hauptmann, killing him instantly.