Unique

Some fellows in the game are Unique. There is only one of each of them in the game. You cannot have two at once. In some cases, once they're gone, they can't be acquired again.

While all commanders have names, Most unique units have fixed names that are outright mentioned in this wiki. For example, Middle Vanheim has many Vanadrotts (22121100%
10%), but only one Vanlade - Vanadrott (32222). There's even a unique unit who always starts as a non-commander, known as Hydra - Daughter of Typhon.

While they currently exist in the world, unique units cannot be Summoned by normal means. For example, there is only one Aella - Queen of Storms; if someone already has Aella, then casting Queen of Elemental Air will not give you her. This works a bit like Artifacts. Death voids a unique unit's obligations towards any faction, allowing the unit to be summoned again; which resurrects them, instead of replacing them with a fresh new clone.

You can Wish for a unique unit that's already in the world, resulting in them being teleported to the Wisher's province. If the unit is not a commander, this switches their allegiance! If the unit is a commander, though, then your Wish will just start a fight. Note that, while you can cast Wish to collect the unique Heroes of other factions before they show up (or while they're dead), they won't be commanders. This is because, other than the Doom Horrors, Wish can't give you commanders.

Pretender Gods are a weird case. Their Recall mechanic is very similar to re-Summoning a dead unique unit, but their bodies lack the "Unique" trait. Thus, if you try to wish for a specific Pretender God, you'll end up with a non-commander "clone" of them; and promoting them to a commander will give them the chassis' base Magic paths, instead of whatever magic the Pretender has.

On this note, Pretender God chassis are the only non-unique units with fixed names.