Dr. Alexander Thorkel is the main antagonist and (semi) title character of the 1940 film Dr. Cyclops, in which he is portrayed by Albert Dekker.
Thorkel was once one of the world's most brilliant biologists, until he began losing his grip on reality. He retired to the jungles of Peru to work in private with the assistance of a former student of his, Peruvian scientist Dr. Mendoza. The two had discovered an abandoned gold mine with a rich deposit of uranium, which Thorkel harnessed for use in his experiments, which involved attempting to reduce the size of living creatures. An extremely secretive man, he trusted only Mendoza. The only other human being he interacted with at all on a daily basis was his Peruvian servant Pedro, who was forbidden from entering the pair's laboratory.
Thorkel's work was only partially successful. None of the shrunken animals he created lived for longer than a day. He always fed them to his pet cat to get rid of the evidence. As time wore on, Thorkel began losing his eyesight. He was forced to wear extremely thick-lensed glasses to correct his vision, but even then, he was almost completely blind, forced to rely more and more on Mendoza to be his eyes, particularly when looking through a microscope. One day, a disagreement between the two scientists led to Thorkel murdering Mendoza, giving him a lethal dose of radiation.
Needing a new pair of eyes, he wrote to an old colleague of his, Professor Kendall, requesting three experts to come to his Peruvian home. Biologists Dr. Rupert Bulfinch and Dr. Mary Robinson are readily available, but the third individual Thorkel requests is unavailable, forcing Bulfinch and Mary to rely on fugitive American engineer Bill Stockton. The three rent mules from miner Steve Baker, who accompanies them to Thorkel's isolated compound.
All Thorkel has them do, however, is take turns looking through his microscope. Their reactions confirm something he has suspected, and, confident he can now correct his error and keep shrunken animals alive for longer than a day, he dismisses the four without any further explanation. Insulted at having been asked to travel thousands of miles just to look through a microscope, however, the four elect to remain and poke around, figuring they deserve an explanation. In retaliation, Thorkel punishes them for their nosiness by shrinking them, along with Pedro, who overheard their discussion. He keeps the five tiny humans imprisoned in his home and studies them, treating them like lab animals rather than human beings.
Bulfinch nicknamed him "Dr. Cyclops." Thorkel initially took this to be a jab at his poor vision, but Bulfinch actually meant to compare him to "the cyclops" from the myth of Ulysses. While measuring Bulfinch, Thorkel realized he was growing and would eventually return to ordinary size. When Bulfinch threatened to go to the police over the matter when that happened, Thorkel panicked and euthanized the shrunken scientist using some ether. However, the others witnessed him kill Bulfinch and fled into the jungle. Thorkel pursued them armed with a shotgun, and shot and killed Pedro. However, he failed to kill Mary, Bill and Steve, who eluded him and doubled back to the house.
Returning to the house, a tired Thorkel fell asleep. The three tiny humans attempted to kill him by pointing the shotgun at his head as he slept, but he awoke and went to his desk to do some work, where he again fell asleep, taking his glasses off. Bill climbed up onto the desk and stole the glasses. Awakening, an enraged Thorkel began tearing the house apart trying to find his shrunken victims turned adversaries, vowing to kill them. He wasted the last of his ammunition attempting to shoot Steve, while Bill broke one of the lenses of Thorkel's glasses. Recovering them, Thorkel put them back on and boasted, "Now you really can call me 'Cyclops!' I have one good eye!"
Using the empty shotgun as a bludgeon, he pursued Mary, Bill and Steve into the backyard, to the well where he and Mendoza had harvested their uranium for their experiments. In attempting to hit the tiny humans with the shotgun, Thorkel accidentally lost his balance and fell down into the well. He saved himself by grabbing a rope, but Bill used a pair of scissors to saw through the rope, dropping "Dr. Cyclops" to his death in the depths of the uranium-filled well.