A Fatality, introduced in the original Mortal Kombat game and had appeared in every game in the series since, is a Finisher performed by the victorious player's character at the end of the match using a specific sequence of inputs before the timer is up.
Staying true to it's namesake, a Fatality is a character brutally killing off the defeated opponent at the end of the match. Fatalities throughout the series all required many different fundamentals for them to properly function. Characters must properly be set in the correct distance from themselves and the opponent for the finisher to initiate. Once the correct input is entered in, an animation would show of the victorious player performing the finisher to which the Announcer promptly exclaim after the execution "(Character's name) wins! Fatality."
While creating Mortal Kombat, Ed Boon and John Tobias, the co-founder founders of the Mortal Kombat series, started with the idea of Street Fighter II-like system and retained many of its conventions, but tweaked others. The most notable additions were graphic blood effects, more brutal fighting techniques, and especially the fatal finishing moves (this was a novelty as the traditional fighting games ended with the loser simply knocked unconscious and the victor posing for the players).
According to Boon, "it started with an idea to enable the player to hit a dizzied opponent at the end of the match with a "free hit", and that idea "quickly evolved into something nasty". According to Tobias: "Our first idea was to use them as a finishing move for the final boss, Shang Tsung, who was going to pull out his sword and behead his opponent. Then we thought, What if the player could do that to his opponent?" When we watched players react to the Fatalities, we knew we had no choice but to give them more."
In Mortal Kombat: Legacy Season I, Baraka uses his Blade Lift Fatality on one of King Jerrod's decoys, and Cyrax performs a Fatality on Hydro, decapitating him with a forked blade from his wrist. Later in Season II, several Fatalities are performed by the various kombatants of the tournament: Kenshi telekinetically thrusts his sword, Sento, through Ermac's heart, Kitana decapitating Mileena with her fans, and Scorpion performs his classic Spine Rip Fatality on Sub-Zero.
- In MK 2011,the characters exclaim a battle cry before performing the finisher. (e.g. Scorpion crouches and fiercely shout; Johnny Cage says "Watch this!").
- There are nine characters in the series who have never received unique Fatalities: Blaze, Chameleon, Daegon, Khameleon, Meat, Mokap, Moloch, Onaga and Taven.