Alexander Bogdanov (1873-1928) invented a blood transfusion therapy intended to achieve eternal youth or at least partial rejuvenation. He died after receiving blood from someone who had malaria, tuberculosis, and had the wrong blood type.

Francis Edgar Stanley (1849-1918) died driving his Stanley Steamer into a pile of wood.

Franz Reichelt (1879-1912) told authorities he would make the initial test of his wearable coat parachute by throwing it with a weighted puppet from the first deck of the Eiffel tower. But he had tricked the authorities, and then he died from the fall.

Harry K. Daghlian Jr. (1921-1945) and Louis Slotin (1910-1946) both died from the radiation they were exposed to while working on the atom bomb.

Horace Lawson Hunley's submarine, CSS Hunley, had failed its first two routine submarine tests before--in 1863--Hunley captained the third, which also failed, and he drowned along with 7 crew members.

Ismail ibn Hammad al-Jawhari (died ca. 1003-1010), a Muslim scholar, fashioned wings from wood and rope and died jumping off the roof of a mosque.

James Douglas, 4th Earl of Morton (1516-1581) introduced the Scottish Maiden to Scotland and was later executed by it.

The Qin dynasty executed Li Si (208 BCE) using the "Five Pains" method that he devised.

Otto Lillienthal (1848-1896) invented the steerable hang glider, crashed it, and died.

Michael Dacre perished in 2009 while testing his flying taxi intended to affordably transport people between regional cities.

Thomas Andrews (1873-1912) was the architect of the Titanic and was aboard when it sank.

William Nelson (ca. 1879-1903) died falling from his motorized bike during a test run.