Boss

The boss is the final opponent that the player must face at the top of the battle plan after having braved their way through the ranks of other fighters. Final bosses are often always computer-controlled only, and thus, are unplayable. Bosses are always inhuman, often demonic, compared to the the cast of characters. In addition, they often possess several advantages over the normal characters such as higher resistance to attacks and much more prominent strength. Victory over the boss results in his climatic demise, followed by the selected kombatant's ending. On rare occasions, the player may unlock a prize for their success.

Mortal Kombat
Shang Tsung's first unplayable and boss role in the entire series. Despite his decrepit appearance, Shang Tsung is a force to be reckoned with. His main form of attack involves launching fireball volleys at his opponent, and each of them very damaging. In addition, he has the ability to morph into any other character in the game, including Goro.
 * Shang Tsung - Goro's Lair

Mortal Kombat 2
Shao Kahn is even more fierce and intimidating than Shang Tsung was. Unlike him, Shao Kahn relies on brute strength, thus most of his attacks are melee oriented, but have a long range and can seriously damage the opponent if off guard. He mainly attacks with single punches and kicks along with a powered charge that comes out rather abruptly.
 * Shao Kahn - Kahn's Arena

Mortal Kombat 3
Even more dangerous than before, Shao Kahn is still an imposing threat to players, though with the changed game mechanics, the battle with him seems much easier. Not much has changed since the last time, though he has replaced his javelin with an eye blast and features a new rising charge attack
 * Shao Kahn - The Pit III

Mortal Kombat 4
One of the very first playable final bosses. Unlike other bosses before him, he is less intimidating, though he possesses the ability to use other characters' movesets.
 * Shinnok - The Well/Elder God Temple

Mortal Kombat Deadly Alliance

 * Quan Chi - Quan Chi's Lair
 * Shang Tsung - Shang Tsung's Palace

Mortal Kombat Deception
The very first blatantly non-human boss in the series. The Dragon King is much more imposing than any other final boss encountered at this point and this fight requires a combination of both strategy and skill. While Onaga can be damaged normally (except for immunity against projectile attacks), Onaga's defense can be weakened by touching any of the Kamidogu lying in place at the edges of the arena. Onaga cannot be defeated by a ringout and the Kamidogu cannot regenerate so you will have to think. Liu Kang is the easiest to defeat Onaga with as he seems to deal double damage to him in particular
 * Onaga - Dragon King's Throne Room

Mortal Kombat Shaolin Monks
Shao Kahn is much more difficult in this battle than he was in MKII but possesses his MK3 moveset. In addition, Shao Kahn can grab the player now and recovers much faster. The safest way to deal damage is by use of projectile attacks and Kintaro's disembodied head. Once Shao Kahn's health is half depleted, his helmet will shatter and begin to make use of his Wrath Hammer only. He makes single, swift upward and downward swings. After at least 4-5 swings, he will begin spinning around with the hammer extended, and the attack can juggle as well, making the attack even more hazardous. After a period of swinging, he will fall into exhaustion. At random, this is merely a hoax. If approached a close range, Shao Kahn will automatically counter you with a grab-and-throw attack. Projectiles is the way to go for this battle.
 * Shao Kahn - Kahn's Arena

Mortal Kombat Armageddon

 * Blaze

Mortal Kombat vs. DC Universe

 * Dark Kahn

=Sub-Bosses=

Mortal Kombat

 * Goro - Dungeon

Mortal Kombat 2

 * Kintaro

Mortal Kombat 3

 * Motaro

Mortal Kombat 4

 * Goro (Home Version only)

Mortal Kombat Deadly Alliance

 * Moloch

Mortal Kombat Deception

 * Noob-Smoke

Mortal Kombat Shaolin Monks

 * Kitana
 * Mileena (secret)
 * Jade
 * Reptile
 * Baraka
 * Sub-Zero
 * Goro
 * Scorpion
 * Shang Tsung
 * Kintaro
 * Ermac (secret)
 * Kano (secret)

Mortal Kombat Armageddon

 * Goro
 * Kintaro
 * Moloch
 * Motaro
 * Onaga
 * Shao Kahn

Mortal Kombat vs. DC Universe

 * Darkseid
 * Shao Kahn