In the Roman Republic, a class that was just below the level of senator. They were also know as 'knights' and had control over administration and finance
Equites legionis
The light cavalry within a legion
Evocatus
A soldier who opted to continue his service in the army after he had been due to retire. Often this was recognised with a promotion too
Equites
Gladiators who fought on horseback
Essedarii
Gladiators who fought from chariots
Excubitores
A new imperial guard instigated by emperor Leo I. They consisted of 300 men drawn from Asia Minor
Extraordinarii
Soldiers set aside for special backup services. This force usually contained 20% of the infantry and 33% of the cavalry