Top: RDX (hexogen) and HMX (octogen), a pair of very powerful high explosives that have seen military use throughout the entire 20th century. RDX was used in the composition of early plastic explosives, and is still used in this application. It was also used for underwater applications in mixtures with TNT and aluminium such as Torpex.
Middle: PETN, pentaerythritol tetranitrate. A vasodilator as well as a high explosive, PETN also heirs from the 19th century but is still used today because of its high effectiveness. Compared to many other energetic substances it is quite non-toxic. An interesting fact is that it can also be considered biodegradable!
Bottom: The old movie star, TNT. Trinitrotoluene, as anyone with a little organic nomenclature quickly will resolve its name to, is excellent for making shells and bombs since it can easily be fused and casted into casings. TNT is the standard measure of explosive power; the nuclear weapon yield unit kiloton is just the explosive power of one thousand tons of TNT. Trinitrotoluene is relatively toxic and generally unpleasant, but very safe with regards to accidental detonation.