There are many classes in Tactics Ogre: Reborn so you'll have plenty of options if you want to experiment with different playstyles. You'll need Classmarks to change to another class and you'll get many of these as you play the game. Some you'll need to buy though, so it makes sense to know how and where you get each one.
In some cases, classes are also limited to race, so I'll go through that below too. It's also worth bearing in mind that there are Classmarks for some monsters, too, but for this guide, I'll concentrate on the generic ones. Here are the Tactics Ogre: Reborn classes and how to unlock them.
Tactics Ogre: Reborn classes: How to get Classmarks
Classmarks items are consumables which let you change class but, as these disappear once used, it's worthwhile knowing where you can get more. Below you'll find a list of the generic classes available in Tactics Ogre: Reborn and how to get the Classmarks associated with them.
Warrior
Races: Human, Winged, Lizardman, Lamia, Orc, Skeleton
Unlock: Sold in shops from Chapter 1
Archer
Races: Human, Winged, Lamia, Orc, Skeleton
Unlock: Sold in shops from Chapter 1
Wizard
Races: Human, Winged, Lamia, Orc, Skeleton, Ghost
Unlock: Sold in shops from Chapter 1
Cleric
Races: Human, Winged
Unlock: Sold in shops from Chapter 1
Rune Fencer
Races: Human, Winged, Orc
Unlock: Sold in shops from Chapter 1
Knight
Races: Human, Skeleton
Unlock: Sold in shops from Chapter 2
Terror Knight
Races: Human, Skeleton, Orc
Unlock: Sold in shops from Chapter 2 or have a chance to drop from exorcised Terror Knight Skeletons or Zombified Terror Knights.
Berserker
Races: Human, Lizardman, Orc
Unlock: Sold in shops from Chapter 2
Dragoon
Races: Human
Unlock: Sold in shops from the middle of Chapter 3 or dropped by Dragoon enemies in Chapter 2
Ninja
Races: Human
Unlock: Sold in shops from Chapter 3 or dropped by Hanzo in Chapter 2
Rogue
Races: Human, Faerie, Imp
Unlock: Sold in Deneb's shop from Chapter 4 or dropped or stolen from Rogues.
Fusilier
Races: Human
Unlock: Recruit Lindl to acquire five Classmarks. These are also rare drops from fusiliers.
Beast Tamer
Races: Human, Winged
Unlock: Sold in shops from Chapter 2.
Warlock
Races: Human, Lamia, Ghost
Unlock: Dropped by witch or warlock enemies.
Necromancer
Races: Human
Unlock: Recruit Cressida to acquire three Classmarks. These are also rare drops from Necromancers in Palace of the Dead.
The final two classes don't need Classmarks to switch—instead you'll need to use a specific item in a set location.
Lich
Races: Human
Unlock: Use a Ring of the Dead to transform a human while on floor 41 of Palace of the Dead.
Divine Knight
Races: Ghost, Skeleton
Unlock: Use an Ensanguined Rood on a Ghost or a Skeleton while on floor three of San Bronsa Ruins.
