| Name | Attribute | Level | Type |
|---|---|---|---|
| Undead Soldier | 85 | General Monster | |
| Undead Specter | 80 | Elite Monster | |
| Undead Specter | 70 | Elite Monster | |
| Undead Specter | 90 | Elite Monster | |
| Undead Specter | 80 | Elite Monster | |
| Undead Spirit Warrior | 83 | General Monster | |
| Undead Villager | - | 1 | General |
| Undead Villager | - | 1 | General |
| Undead Villager | - | 1 | General |
| Undead Wanderer | 43 | General | |
| Undead Warrior | 83 | General Monster | |
| Underground Crustdrone | - | 80 | General Monster |
| Underling 1 | - | 1 | General |
| Underling 2 | - | 1 | General |
| Underling 3 | - | 1 | General |
| Undying Elegance | 110 | General Monster | |
| Undying Elegance | 110 | Elite Monster | |
| Unexpected Harvest | - | 1 | General |
| Unexpected attack | - | 1 | General |
| Unexplored Places | - | 1 | General |
| Unholy Automaton Rex Machina | - | 20 | World Boss |
| Unholy Automaton Rex Machina | - | 20 | World Boss |
| Unholy Automaton Rex Machina | - | 90 | World Boss |
| Unholy Automaton Rex Machina | - | 30 | World Boss |
| Unholy Flame | - | 64 | Elite Monster |
| Unholy Flame | - | 64 | Elite Monster |
| Unholy Sprite | 55 | General Monster | |
| Unidentified Ghost | - | 1 | Interactive |
| Unidentified Ghost | - | 1 | General |
| Unknown Creature | - | 1 | General |
| Unknown Dimension | - | 1 | General |
| Unknown Dimension | - | 1 | General |
| Unknown Dimension | - | 1 | General |
| Unknown Dimension | - | 1 | General |
| Unknown Dimension | - | 1 | General |
| Unknown Dimension | - | 1 | General |
| Unknown Dimension | - | 1 | General |
| Unknown Samurai | - | 1 | General |
| Unknown Woman | - | 1 | General |
| Unknown attacker | - | 1 | General |
| Unknown treasure | - | 50 | General Monster |
| Unknown treasure | - | 50 | General Monster |
| Unmoved Box | - | 70 | Interactive |
| Unstable Energy | 68 | Boss Monster | |
| Unstable Energy | 63 | Boss Monster | |
| Unstable Energy | 63 | Boss Monster | |
| Unstable Energy | 63 | Boss Monster | |
| Unstable Energy | 73 | Boss Monster | |
| Upgrade Device | - | 1 | General |
| Urmaz | - | 1 | General |