UnitName

Returns the name and realm of the unit.

name, realm = UnitName(unit)
            = UnitFullName(unit)
            = UnitNameUnmodified(unit)

Arguments

name: string? - The name of the unit. Returns nil if the unit doesn't exist, e.g. the player has no target selected.
realm: string? - The normalized realm the unit is from, e.g. "DarkmoonFaire". Returns nil if the unit is from the same realm.

Will return globalstring UNKNOWNOBJECT "Unknown Entity" if called before the unit in question has been fully loaded into the world.
The unit name will change if the unit is under the effects of [Lifegiving Seed] or a similar effect, but UnitNameUnmodified() is unaffected by this.

/dump UnitName("player") -- "Leeroy", nil

/dump UnitName("target") -- "Thegnome", "DarkmoonFaire"

UnitFullName() is equivalent with UnitName() except it will always return realm if used with the "player" UnitId.

/dump UnitFullName("player") -- "Leeroy", "MoonGuard"
/dump UnitFullName("target") -- "Leeroy", nil

GetUnitName(unit [, showServerName]) can return the combined unit and realm name.

If showServerName is true and the queried unit is from a different server, then the return value will include the unit's name appended by a dash and the normalized realm name.
If showServerName is false, then FOREIGN_SERVER_LABEL " (*)" will be appended to units from coalesced realms. Units from the player's own realm or Connected Realms get no additional suffix.

Unit is from the same realm.

/dump GetUnitName("target", true)  -- "Nephertiri"
/dump GetUnitName("target", false) -- "Nephertiri"

Unit is from a different realm but the same Connected Realm (LE_REALM_RELATION_VIRTUAL).

/dump GetUnitName("target", true)  -- "Standron-EarthenRing"
/dump GetUnitName("target", false) -- "Standron"

Unit is from a different, non-connected realm (LE_REALM_RELATION_COALESCED).

/dump GetUnitName("target", true)  -- "Celturio-Quel'Thalas"
/dump GetUnitName("target", false) -- "Celturio (*)"