These units are first introduced in Chapter 1 where they spawn from a portal. They are officially given the name Risen in the next chapter. They are humans who were killed and reanimated into undead warriors by Grima. It is later revealed that many of the Risen that spawned in the current time actually came from the future through the portal that Grima created to prevent Lucina and the other children from altering the future. According to Brady, even wounded people can potentially become Risen. Risen usually carry little sentience, and speak in fragments rather then full sentences; however, as time passes their words become much more clearer and they can speak in full sentences without struggling in saying words. When a Risen is slain, their bodies turn into dark dust which dissipates quickly.
Risen also have human qualities to them, but it is very likely that they seem to fade as time passes. This is shown in Death's Embrace, where killing specific classes results in them thanking the player for ending their torment. They may also appear to have a desire to belong, as they always seem to be attacking places where groups of people like to gather, as shown in Hot-Spring Scramble.
It is possible for even people to create Risen, as Henry's support conversations with the Avatar show that he brings a severed Risen hand for examination and ends up managing to create an army to ward off a large group of enemies later on. Algol possibly is able to create Risen also, as in the DLC Death's Embrace shows that he refers them as his minions, is the only human enemy in that DLC and they do not attack him.
While Risen are composed of various human classes and are mostly male dominated, there are also female Risen that correspond to female-exclusive classes such as Pegasus Knights and Valkyries. They often wield weapons suited to their classes, the rank of which depend on the game difficulty or chapter, but they can also carry other weapons they may drop when they're defeated. There are also grunt Risen, Revenants and Entombed, that can attack with strong Claws and Talons. They are sometimes led by the more powerful Risen Chiefs (Corpse Generals in the Japanese version).
Risen may also pop up in random locations once every hour of in-game time, and disappear from those locations. Completing a Chapter or Paralogue can cause Risen to spawn without waiting, but they do not have a 100% chance to appear. Using a Reeking Box will spawn them at the player's location immediately, provided there is nothing else occupying that location.
Due to their random spawning pattern, the following may happen should they appear with one of the following:
- Risen and Risen: The player fights two groups of Risen at once, with the two commanders being in the spots they may spawn in individually. After defeating both groups, the player receives 3000 Gold and a random B-rank weapon or a stat boosting item.
- Risen and Merchant: A Merchant appears on the field, usually in a place close to the player's position. If the Merchant survives the skirmish, the player will receive an item from her and she will open her shop afterwards; if the Merchant does not survive, she will disappear with the Risen.
- Risen and Outrealm Team: The Outrealm team will act as your allies for the duration of the skirmish. Any casualties suffered on the team will not affect the ability to parley with them afterward unless the leader is killed, in which case the team will vanish along with the Risen.
- Deadlords - Twelve undead warriors and recurring characters that first appeared in the Jugdral Series. They appear as Risen in Chapter 22 and the Xenologue chapter Infinite Regalia.
- The Risen's name likely comes from the fact they were humans who were killed and reanimated by Grima and therefore have "risen" from death.
- Though they are officially given the name Risen in Chapter 2, selecting one with the cursor in Chapter 1 will reveal their name prematurely.
- When facing Risen Generals and Great Knights in battle, they will have the generic Risen face on them, even though their human counterparts only show their helmet instead. This is odd, considering that Risen Warriors wear a helmet and do not show the generic risen face.