The Spanish Influenza of 1918-1920.
The 30.cal machine gun.
According to wikipedia it was World War 2 with 70 million people killed, most of whom were civilians. http://en.wikipedia.org/wiki/World_War_II
Well, technically speaking, Nazi Germany did by far since they killed so many Jewish people.
Although it is now eradicated I believe it was smallpox.
Ciudad Juarez, Mexico is dangerous. About 85 people a day are killed.
The most rare illness ever is one that is not diagnosed. People with this illness die of unknown causes because it is so rare that it is not functionally documented.
Most were killed from the explosion, some survived but may have short term or long term radiation illness which can be terminal.
According to recent research, the animal that kills the largest amount of people is the Theraphosa Blondi. The Theraphosa Blondi is a ten-inch long spider, that attacks whatever it sees that moves. I wouldn't want to run into one of those in a dark alley!
Most of those killed were gassed to death.
The disease that killed most of Edgar Allan Poe's female family members was tuberculosis. It was a common and deadly illness during that time period, and sadly, it took the lives of many people, including Poe's loved ones.
The volcano in Indonesia has killed the most people. It killed 92,000 people.
1970 Bhola Cyclone killed 300,000-500,000 people.