Man

Woman

Human

Demon

Divine

Insect

Mechanical

Dragon

Beast

Aqua

Flying

Ice

Fire

Lightning

Nature

Poison

Undead

Wraith (should not be mistaken with story Wraith units)
Receive 25% damage and deal 25% damage except for other Wraith or units in Slay list.
No effect from Defense Formation and Forward Guard skills.
Heal only with Wraith Recovery.
More details at the in-game tutorial.

Knight

Night
Units have only 50% defense when fighting during the day.
(Not Night units are Day units and have 50% defense when fighting during the night).

Supreme
Not afflicted by status ailments.

Same as Slay All skill.
Appears only in Slay list, so not the actual unit type.