In Ragnarok Online, Expanded Classes were named classes that didn't had evolutions, fact that changed after the appearance of the Oboro/Kagerou class. Adapting this concept to MouRO, an Expanded Class can be named a class that can only be evolved to after Rebirthing. The classes included in this category are the: Ninja, Gunslinger and Taekwon branch.
Differently from the Officials' and Vanilla Private's styles, in MouRO the Expanded Classes aren't achieved by directly evolving a Novice into them, instead, you must either evolve into them from a High Novice, or a High First Class.
- Ninja: In MouRO, Ninjas are Advanced Second Classes of Thieves, which means that to acquire a Ninja one must get a High Thief, and then evolve from them by choosing between Stalker, Assassin Cross and Ninja.
- Gunslinger: In MouRO, Gunslingers are Advanced Second Classes of Merchants, which means that to acquire a Gunslinger, one must get a High Merchant, and then evolve from them by choosing between Whitesmith, Creator, and Gunslinger.
- Taekwon: In MouRO, Taekwons can only be acquired if the character was, before rebirthing, a magic class. That means that one can only become a Taekwon by choosing to be either a Mage class, or Acolyte class before rebirthing. After rebirthing when becoming a High Novice, before turning into the High First Class (either High Acolyte or High Mage) a second option will appear for you, which will be the Taekwon. By doing so, after choosing the Taekwon, the player will be able to play it normally, and eventually change into either the Star Gladiator, or Soul Linker classes.