There has never been a peace treaty, so the Korean War has technically never ended. (..)

U.S. Troops Statistics
Source: Dept. of Defense
U.S. Deaths:
Hostile: 33,739
Non-Hostile: 2,835
Total In-Theatre: 36,574
U.S. Wounded in Action – 103,284

Other Casualties by Country (killed and missing)
Source: Encyclopedia Britannica
South Korea – (217,000 military, 1,000,000 civilian)
North Korea – (406,000 military, 600,000 civilian)
China – (600,000 military)