Wenger
Wenger have been supplying the Swiss Army for over 100 years, and their knives are known as "The Genuine Swiss Army Knife".
Originally called The Swiss Officer's Knife, the Americans called them The Swiss Army Knife, and this term has stuck.
They became world famous during WW2 when US soldiers found them extremely useful.
The Soldier's Knife
When Wenger (and Victorinox) first started supplying the Swiss Army, soldiers needed a screwdriver to maintain their rifles. For this reason the knife supplied included a screwdriver, and for good measure a reamer and a can opener were added.
This knife was called the Soldier's Knife, and they later produced the Swiss Officer's Knife, which was a bit lighter and had a few more functions (including a corkscrew!).
Officers in the Swiss Army were never actually issued with The Swiss Officer's Knife, however. All members of the Swiss Army are only ever issued with the Soldier's Knife.