Death

Death is the all encompassing force that eventually affects all humans, ghosts, snakes, and several other beings from Ninjago and the other realms. It is the cessation of the functions that allow a living or undead being to continue to exist in the living world. It is the only known way to gain entry into the Departed Realm.

Humans

 * Dr. Julien (formerly resurrected by Samukai, now departed once more)
 * Captain Soto (formerly; resurrected by the Mega Weapon)
 * The rest of the Destiny's Bounty crew (formerly; resurrected by the Mega Weapon; one was disintegrated by the Mega Weapon and is now departed once more)
 * Dilara (spirit formerly resurrected through Nya by Nadakhan, now departed once more)
 * Nya (in an alternate timeline)
 * Cliff Gordon
 * Emperor of Ninjago
 * Empress of Ninjago
 * Hutchins
 * Cole's Mother
 * Harumi's Father
 * Harumi's Mother
 * Harumi (possibly)
 * Several Elemental Masters
 * Several Cloud Kingdom monks
 * Several other humans

Skulkin

 * All Skulkin are undead except Samukai, who was sent to the Departed Realm.

Serpentine

 * All Anacondrai except Pythor.
 * Anacondrai Serpent
 * The Great Devourer

Stone Army

 * All except the Giant Stone Warrior

Overlord Faction

 * All except some in Kryptarium and others, who were reprogrammed and became Cyrus Borg's Security Droids.

S.O.G. Faction

 * Mr. E

Anacondrai Cultists

 * All except Clouse and Skylor.

Cursed Ghosts

 * All Ghost Warriors, who were imprisoned in the Cursed Realm.
 * Morro in the Departed Realm.

Djinn

 * All except Nadakhan

Oni/Dragon Hybrids

 * First Spinjitzu Master

Oni/Dragon/Human Hybrids

 * Garmadon (formerly; resurrected by the Oni Masks)

Oni

 * Mistaké (possibly)

Unknown

 * The Preeminent

Realms of the Deceased
In the Sixteen Realms, there were a total of three known realms for the dead to continue to dwell after their passing. Of the three, the Departed Realm seems to be where the dead are naturally supposed to go, as when a being who was sent to the other two is destroyed, their spirit will move on to the Departed Realm.
 * Departed Realm (for all denizens of all Realms)
 * Underworld (for fallen warriors who were disgraced in battle, and don't accept or realize their passing)
 * Cursed Realm (for those who's souls are cursed; destroyed)

Returning to Life
Death can be also thwarted, but the ways that this can be accomplished are extremely dangerous and unstable, as it goes against the natural order of the world. Likewise, the consequences of such methods on users can prove too dire or even worse than death itself. These are some ways to trick death:
 * Resurrectea (Temporary postponement of Death)
 * Rift of Return (Requires powerful magic from the Yin-Yang Eclipse to sustain)
 * The power of the Yin Blade (Places victim into a state of ghost-like limbo)
 * Being wished into the body of another living being by a Djinn King (Possession of another person)
 * Killing one's murderer with a Departed Blade
 * Magic/Dark Magic
 * Escaping from the Cursed Realm or Underworld (Escapee is left in an undead state of being, either skeletal or cursed)
 * Resurrection by the Mega Weapon (Massive energy toll on user required)
 * Reversing time on the corpse of the deceased (Negated by Tomorrow's Tea)
 * Escape from the Departed Realm (Requires a massive amount of catalyzed magic to sustain indefinitely)
 * Imprisonment in the Djinn Blade (Indefinite, unconscious limbo for all eternity)
 * Oni Masks (When they are united; exclusive to those of Oni descent)