Touching on the Templar myth above, general "history" has presented the Knight's Templar as a cool and sinister group of badass warrior monks/priests who may or may not have formed the Illuminati, worshiped the devil and knew black magic. The Knights Hospitaller on the other hand? Kind old men with beards who healed people rather than smite evil.
The truth? Rather different.
If nothing else the fact that the Hospitallers were an effective military (although many would use the term "pirate" instead) force till virtually the 1800's (including holding off Napoleon briefly) should be a testament to how badass they could be. Likewise the sieges of Rhodes and Malta both probably deserve to be given a lot more attention then they are, representing a triumph (even if Rhodes was technically a defeat) over outrageous odds. I'm not a huge fan of putting a vast amount of "what if..." significance in single events but if Malta had been lost I don't see how it wouldn't have had a significant impact on European history. The Ottoman Empire was at its peak, Suleiman the Magnificent was looking to the West, the route to Austria and Hungary was pretty much open and he had Turgut Reis, arguably the finest admiral/reaver of his era. Malta was a perfect staging ground for further attacks into the heart of a divided Europe... and all that held it were between 6,000 and 8,000 troops including about 500 Hospitillers (a constant thorn in the Ottomon Empire's side) led by Jean Parisot de Valette, a man who had previously been enslaved by Reis and forced to serve on a galley and at between 67 and 70 years old a clear contender for most grumpy/bad ass pensioner of all time.
Despite having one of their fortresses being pretty much literally flattened, having to take the biggest sustained bombardment history recorded up to that point and a third of the population (not just the troops... the population of Malta) dying, those Hospitillers held off between 20 and 40,000 invaders, killed Reis (albeit somewhat by luck), and inflicted pretty shocking casualties, breaking the back of the elite forces of the Ottoman army and navy. The fact that in an age of gunpowder, cannons and muskets the knights were apparently still wearing plate mail makes it seem even more ridiculously bad ass.
So, here's the thing. The Templar's may have the edge in conspiracy theories and dubious monetary practices (although with their tendency to proclaim anything shiny and valuable as being an "infidel good" which meant it could be captured and resold for the profit of the Order, the Hospitallers' weren't beyond that themselves) but in terms of being all out warrior monks? The Knights Hospitaller deserve more credit.