How many died in the Korean War? There are widely varying reports:
North Korea and the United States: Will the Real Aggressor Please Stand Down? quotes S. Brian Willson indicating four million Koreans were killed: three million in North Korea and one million in South Korea, and one million Chinese. That would be a total of five million, not counting US and allied casualties.
Korean War indicates nearly five million people died, of which over half were civilians. It also indicates almost 40,000 US dead. Presumably the US fatalities were part of the almost five million total casualties.
Korean War indicates a very different total: 1.2 million total deaths, based on 'recent scholarship' reported in http://www.eui.eu/Documents/DepartmentsCentres/SPS/Seminars/SeminarsF09/PVSEMF08/LacinaGleditschMonitoringTrendsInGlobalCombatEJP2005.pdf.
http://www.historylearningsite.co.uk/korean_war.htm indicates 1.3 million South Korean military, 520,000 North Korean military and over 3 million Korean civilian casualties. Also, 142,000 US casualties, 900,000 Chinese casualties and 17,000 UN casualties. That's a total of almost six million casualties. This may be dead and injured.
http://www.cotf.edu/ete/modules/korea/kwar.html indicates four million casualties, including 33,600 US, 16,000 UN, 415,000 South Korean and 520,000 North Korean dead. That's 984,600 dead. It also indicates 900,000 Chinese casualties but it is unclear if these are part of or additional to the four million casualties.
http://necrometrics.com/20c1m.htm#Ko presents figures from various sources. They are quite variable. Total deaths reported range from about 2 million to 3.5 million.
With such variation in numbers reported, the actual number of deaths is uncertain, but it seems that more than 1 million and possibly several million people died. That's a lot of people in a brief conflict and a smal part of the world.
