Missing Link is a superhumanly strong Neanderthal-like humanoid whose body absorbs and emits radiation. Eventually the Missing Link builds up so much radiation that he explodes, but can then reconstruct his body.
The creature known as the "Missing Link" in modern times was born countless millennia ago. He was sealed in an underground pocket during a volcanic eruption, and somehow survived into modern times. A Chinese atomic test caused a rift to open in the ground, spewing magma to the surface, and a few days later the creature crawled out, mutating into a radioactive monster. The Chinese captured the creature, and placed him in a lead-lined capsule aboard a freighter from another Communist country.
The ship's crew launched the capsule towards New York harbor, where the Missing Link emerged and rampaged. It fought the Hulk, until both were captured by Russian Colonel Yuri Brevlov. The Hulk broke free, which released the Missing Link as well; the Missing Link exploded into thousands of tiny pieces from radiation buildup.
Eventually, its body reconstructed itself in the Appalachian Mountains of West Virginia. The Brickfords, a local family, found him and cared for him. The Brickfords named him "Lincoln", educated him, and got him a job in the mines. The Brickfords also took in Bruce Banner soon after. Bruce recognized who Lincoln was after Jimmy-Jack Brickford fell sick from radiation poisoning due to exposure to Lincoln. Bruce tried to confront Lincoln to get him to leave the Brickfords, but Lincoln did not believe him and attacked. As the Missing Link fought the Hulk, his touch burned the Hulk and he realized that Banner was telling the truth just as he reached critical mass and exploded again.
When Lincoln reformed into a solid form again, he continued to live with the Brickfords and work in the mines. The mines began to leak toxic fumes, making people leave or become sick. Lincoln realized this was his fault, and he hid in the mines. The Spaceknight Rom detected the radiation and investigated, curing the Brickfords of their radiation poisoning. Rom found Lincoln and explained to him that he was a threat to the entire planet. Rom used his neutralizer to purge Lincoln of radiation.
However, the town could not be rebuilt, and the Brickfords were forced to turn Lincoln over to the authorities and they moved out west.