More commonly called the "Huey" than its formal name, the UH-1 Iroquois is quite possibly the most recognized military helicopter in the world. Along with the M-16 rifle, it is an icon of the Vietnam War. While there are many variants, the original U.S. Army requirement was for a light tactical transport helicopter, principally for medical evaluation. In Vietnam, armed helicopter variants soon appeared, and eventually the dedicated AH-1 Cobra attack helicopter derivative.
Over 15,000 have been built, more than any other helicopter. 
Developed by Bell Aviation as its Model 204, it was among the first helicopters powered by a turboprop rather than piston engine. Before the consolidation of the Army and Navy aircraft designation systems, it was known as the XH-40, and then became Utility Helicopter 1 (UH-1) in the joint designation system.
Model 204 variants
Model 205 variants
These helicopters, starting with the UH-1D and ending with the UH-1H, had an extended body and more powerful single Textron Lycoming T53-L-13 turboshaft engines.
- Bell UH-1 "Huey", U.S. Century of Flight Commission