Does your setting have famous units of renown, elite brotherhoods and grand orders that are known far and wide?

It is rare for a serf to escape the trappings of his caste, but by His Majesty's decree, all peasant-bachelors from ages 16 to 35 must serve in their lord's army "with bowe and arrowe".
Practise of the bow is both required by law and actively encouraged by state-sponsored competitions, wherein a humble serf may win a sizeable purse for his efforts. Champion archers of sufficient skill (supposedly, they must be able to cut a man's purse at 300 paces with nought but an arrow) are pressed into service as full-time soldiers, serving both as an elite unit of archers, and as commanders of regular archers during war.

They are if they do it for money

The Themistian Knights of the sacred elven lands are an handful at best, but each is worth an army.
Protecting what the legends told to have been the home of the gods when they walked the earth, they hold sacred power and antique artefacts beyond mortals limits.
Distinguished by their holy (and semi-sentient) armour after accomplishing many herculean feats, they dedicate their life to the service of long departed gods.
Actually shameless not-saint-seiya saints that started as a joke, but I'm planing to use them as terrifying antagonists.

Definitely stealing this.

A direwolf is wild - it is reckless, and unreliable - but it can be trusted to run with it's pack, and thereby can be controlled.
No 'civilised' army has ever employed the use of mounted wolves, but the Wildmen under the banner of the Chimera have, to great effect. Though rarely suited to open battle, wolf-riders are the proverbial right hand of guerilla warfare, able to traverse forested terrain at unparalleled speed, to move almost entirely without trace, and to wreck utter havoc upon an enemy's most vulnerable positions and supply-lines.

The landless knights of the prince of Alonguin. Originally formed by the son of a relatively minor prince in one of the major empires they were originally drawn from the biggest and strongest men from each village his father had dominion over. The princeling then trained and equipped these large and strong men with full suits of armour, lances, war hammers, and horses.

During one of the numerous conflicts in the region the knights proved themselves extremely capable and slowly grew in number allowing men in any town they crossed through to challenge a champion, and if they won they would be accepted into the knights fighting unarmoured with spare weapons until they could be properly fitted with armour. After the princeling succeeded his father he named his son leader of the knights , who continued their practices often selling themselves as mercenaries during times of peace.

Despite the names some knights do eventually gain lands and titles either by the prince of Alonguin or as thanks by some lord they are serving under, and as they are conventional servants of the prince of Alonguin nothing inherently mandates that one be landless to serve. Many young peasant boys dream of having the knights pass through their village and defeating a champion as it is the only way for the vast majority of peasants to climb the social ladder. Although not allowed to take their family with them initially, upon becoming settled in the unit most knights return for their families.

The Band of the Summer Moon, aka 'Night Drinkers', 'White Hands', or the Black Banner
>Elite warriors drawn from all across the constituent tribes of the Iztacan who have been inducted into a military society sworn to the Exiled God. They proudly decorate their panopolies with handprints of white paint and coyote motifs in His honor, for just as the Exiled God gave up everything for His people so shall they, if need be.
As vanguards they serve as scouts, heralds, runners, & escorts - ensuring armies can remain in constant communication.
In pitched battles they serve as fearsome shock troops or as bulwarks to fill broken lines.
In the case of retreat the Black Banner always tarries behind at the very rear of the army, harsssing/ambushing and slowing the enemy so their comrades can escape.

Probably the most famous military unit in my setting's recent history is the Desten, who are an elite military brotherhood in the dominant empire on the continent. They're not technically subjects, they're more like a semi-autonamous religious order dedicated to kicking people's heads in who view the head of state as a living deity.

That being said, they've gotten the shit kicked out of them in the war that most of the campaign has turned into, so their star is fallen, possibly all the way into the sea.

The Holy Order of the Pale Torch. It's not clear how members are chosen and membership lasts for life (and involves being made immortal).
They fight devils.

One word.

Janissaries.

shit dude, I was trying to refine my fire archer idea but, Janissaries would fit really good. mind if I take that idea?

>muh praetorians

Ugh.