For those of you that want to make a historical version of this heres a bunch of data.
* Accensus - either a public officer who attended on several of the Roman magistrates; or a kind of supernumerary soldier who served to fill the places of those who were killed or disabled by their wounds in the Roman Republic
* Adscripticius - a supernumerary soldier of the Roman Republic who served to fill the places of those who were killed or disabled by their wounds.
* Antesignani - Vanguard troops. Antesignani means "those before the standard" (Signus, Signum)
* auxilia - troops in the Roman army of the late Republican and Imperial periods who originally stayed in their home province but were formalised and later took on the role of providing specialist support to the legions. An example would be the Syrian archer.
* Balearic slingers - Expert slingers from the Balearic Islands off the Mediterranean coast of modern Spain.
* bucelarii - a unit of soldiers in the late Roman and Byzantine empire, that were not supported by the state but rather by some individual such as a general or governor.
* cataphractarii - heavily armed and armoured cavalrymen, adopted from the Parthians and first deployed by the Romans in the 2nd Century AD during the reign of emperor Hadrian.
* Classiarii -Roman Marines
* Celeres - a force of 300-500 probably cavalry that served as a bodyguard to the early Roman kings. Their name Celer is Latin for "the swift".
* Clibanarii - a military unit of heavy armoured horsemen similar to the Cataphracti
* Cohortes urbanae - a police unit of urban Rome and sometime counterbalance to the power of the praetorian guard.
* Comitatenses - the standard legionnaire after the reforms of Constantine
* Comitatenses Palatini or Auxilia Palatini- a central field army of the late Roman Empire that was unique in that it was always under the direct command of the Roman Emperor
* Contarià - cavalry equipped with the contos (kontos), a very long lance
* dromedarii - camel riding auxiliary forces recruited in the desert provinces of the east Roman empire
* Duplicarius - officer in the army
* Equites - Roman citizen horse troops drawn from the Roman equestrian class.
Equites
* Foederati - soldiers provided by barbarian tribes in return for subsidies
* frumentarii - the secret service of the Roman Empire.
* Hastati - the first line of battle in the Roman Republican Army.
* herculiani - the imperial guard of the Emperors of the Roman Empire from 284 until 988
* Ioviani (also called Jovians) - the imperial guard of the Emperors of the Roman Empire from 284 until 988
* Lancearii - Spear armed mail clad field troopers that supported the comitatenses
* Latini - allied troops of the Republic provided by non-citizens living in allied Latin towns
* Limitanei- Lighter late legionaries similar to the auxilia of Caesar's day normally use in garrison.
* Menapian spearmen - More few and at best auxiliary mercenaries.
* Nabataean archers - Auxiliary bowmen recruited from Nabataea, in what is now southern Jordan.
* Numerii - A loose term for any soldier
* pedites - the infantry of the early army of the Roman kingdom. The majority of the army in this period.
* Peditatus - a term referring to any infantryman in the Roman Empire
* praetorians - a special force of bodyguards used by Roman Emperors
* Principes - the second line of battle in the Roman Republican Army. They were also chieftains in Briton like Dumnorix of the Regneses (he got killed by Gaius Salvius Liberalis' soldiers)
* Rorarii - the final line, or reserve, in the ancient pre-Marius Roman army. These were removed even before the reforms as the Triarii provided a very sturdy anchor
* Sagittarii - archers, including horse-riding auxiliary archers recruited mainly in the Eastern Empire and Africa
* Scholae Palatinae - an elite troop of soldiers in the Roman army created by the Emperor Constantine the Great to provide personal protection of the Emperor and his immediate family
* Socii - Conscripts
* speculatores - the scouts and reconnaissance element of the Roman army
* supernumerarii - a kind of supernumerary soldier who served to fill the places of those who were killed or disabled by their wounds
* Triarii - the third standard line of infantry of the Roman Republic's army
* Velites - a class of light infantry in the army of the Roman Republic
* Vigiles - the firefighters and police of Ancient Rome