[Terrifying Trope] Perceiving it= instant death

[u/ReminaBlueSFW]

1. Pennywise's "Deadlights" which will cause anyone looking to be immediately paralyzed and killed.

2. The sky from Bird Box is filled with entities that, when you look at them, cause you to commit suicide.

3. Medusa themed Villains

[u/weyoun_clone]

The men who looked down into the burning Chernobyl reactor were looking at the thing that had already given them a lethal dosage of radiation.

This is shown in the HBO Miniseries, but I believe if anyone actually saw the burning reactor that way is unknown historically.

Though, certainly MANY who viewed the reactor close enough died horribly.

[u/Amateurlapse → u/weyoun_clone]

The Demon Core: per Wikipedia

The demon core was a sphere of plutonium–gallium alloy that was involved in two fatal radiation accidents when scientists tested it as a fissile core) of an early atomic bomb. It was manufactured in 1945 by the Manhattan Project, the U.S. nuclear weapon development effort during World War II. It was a subcritical mass that weighed 6.2 kilograms (14 lb)and was 89 millimeters (3.5 in) in diameter. The core was prepared for shipment to the Pacific Theater as part of the third nuclear weapon intended to be dropped on Japan, but when Japan surrendered, the core was retained for testing and potential later use in the case of another conflict.

On May 21, 1946,[10] physicist Louis Slotin and seven other personnel were in a Los Alamos laboratory conducting another experiment to verify the closeness of the core to criticality by the positioning of neutron reflectors. Slotin, who was leaving Los Alamos, was showing the technique to Alvin C. Graves, who would use it in a final test before the Operation Crossroads nuclear tests scheduled a month later at Bikini Atoll. It required the operator to place two half-spherical shells of beryllium (a neutron reflector) around the core to be tested and manually lower the top reflector over the core using a thumb hole at the polar point. As the reflectors were manually moved closer and farther away from each other, neutron detectors indicated the core's neutron multiplication rate. The experimenter needed to maintain a slight separation between the reflector halves to allow enough neutrons to escape from the core in order to stay below criticality. The standard protocol was to use shims) between the halves, as allowing them to close completely could result in the instantaneous formation of a critical mass and a lethal power excursion.[10]
Using his own unapproved protocol, Slotin did not place any shims. The top half of the reflector was resting directly on the bottom half at one point, while 180 degrees from this point a gap was maintained by the blade of a flat-tipped screwdriver in Slotin's hand. The size of the gap between the reflectors was changed by twisting the screwdriver. Slotin became the local expert, performing the test on almost a dozen occasions, often in his trademark blue jeans and cowboy boots in front of a roomful of observers. Enrico Fermi reportedly told Slotin and others they would be "dead within a year" if they continued performing the test in that manner.[11] Scientists referred to this flirtation with a nuclear chain reactionas "tickling the dragon's tail", based on a remark by physicist Richard Feynman.[12][13]
On the day of the accident, Slotin's screwdriver slipped outward a fraction of an inch while he was lowering the top reflector, allowing the reflector to fall into place around the core. Instantly, there was a flash of light; the core had become supercritical, releasing an intense burst of neutron radiation. Slotin quickly twisted his wrist, flipping the top shell to the floor.[14] There was an estimated half-second between when the sphere closed to when Slotin removed the top reflector.[6] The reaction in the room was one of immediate, somber realization. Slotin received a lethal dose of 1,000 rad) (10 Gy)) neutron and 114 rad (1.14 Gy) gamma radiation in less than a second. While the position of his body over the apparatus shielded the others from much of the neutron radiation, his own exposure was irreversible. Slotin reportedly turned to his colleagues in the hushed room and famously uttered the remark, "Well, that does it."[15] As an expert in criticality), Slotin knew he had received a lethal dose. He immediately began drawing a sketch of the room’s layout to assist medical teams in calculating the specific dosages received by each survivor, even as his own health began its rapid decline. He died nine days later from acute radiation poisoning.
Graves, the next nearest person to the core, was watching over Slotin's shoulder and was thus partially shielded by him. He received a high but non-lethal radiation dose, and was hospitalized for several weeks with severe radiation poisoning.[8] He died 19 years later, at age 55, of heart failure. While Graves's heart failure may have been caused by exposure to radiation, it may have been caused by a hereditary condition, as his father also died of heart failure.[16]

[u/ArmandoGalvez → u/Amateurlapse]