It should be noted that the a lot of heavy (and in some cases, medium and even light) trucks of many countries have semi-tractor variants of those vehicles.  For most of these, I have only very sketchy details and they are not included here.  In a similar vein, I have not been able to find much in the way of civilian semi-tractors (or civilian heavy trucks and equipment in general), and they are not included here.  Perhaps in the future...

Australian Semi-Tractors

Austrian Semi-Tractors

British Semi-Tractors

Chinese Semi-Tractors

Czech Semi-Tractors

Dutch Semi-Tractors

French Semi-Tractors

German Semi-Tractors

Greek Semi-Tractors

Italian Semi-Tractors

Japanese Semi-Tractors

Russian Semi-Tractors

South Korean Semi-Tractors

Spanish Semi-Tractors

Swedish Semi-Tractors

US Semi-Tractors

Yugoslavian Semi-Tractors