Kefka Palazzo (Japanese: ケフカ・パラッツォ, Hepburn: Kefuka Parattso; romanized as Cefca in the Japanese version) is a fictional character and the main antagonist of the 1994 role-playing video game Final Fantasy VI, developed by Square. Yoshitaka Amano created his visual design and director Yoshinori Kitase wrote his scenes. He is one of the most well-known and well-received villains in the Final Fantasy series. He was given a featured role in the fighting game Dissidia Final Fantasy and its sequels. He also appears as an enemy boss character in games including Theatrhythm Final Fantasy, Final Fantasy Artniks, Final Fantasy XIV, and Final Fantasy All the Bravest.

Kefka is first introduced as the court mage of Emperor Gestahl. Over the course of the game, he reveals himself to be a nihilistic psychopath, gone mad from the cruel experiments that gave him his magical powers. When Gestahl is poised to seize the source of magic in the world, Kefka betrays him and takes it for himself. With his new godlike powers, Kefka rules the remains of a ruined world with an iron fist.

Kefka is considered one of the most memorable video game villains ever created, with critics and fans noting his intense hatred and maniacal laughter as defining characteristics. He has also been compared to the Joker from the Batman franchise.

Kefka's appearance was designed by Yoshitaka Amano, who was given complete creative freedom in Final Fantasy VI, with only brief character outlines as guidelines. His approach was to create "real" and "alive" characters, though with consideration for their representation as small computer sprites. Several designs were created for Kefka during the planning stages, each with different outfits, taking inspiration from clowns seen at circuses. Amano felt the character was akin to DC Comics villain Joker, and wanted to illustrate a character that shared Joker's crazy personality, someone that was "completely insane". He found the overall process fun to develop.

Writer Yoshinori Kitase found the original writing "did not give him much character", and while working on the very first scene developed for the game, Kefka's approach to a castle, Kitase felt it was too boring to do normally. He added a scene off the top of his head where Kefka demanded soldiers dust off his boots in the middle of a desert, meaning for it to imply that there "may be a screw or two missing from this character's head", something he felt was a perfect fit for Kefka and helped define the character's personality for the rest of the story. In an interview with Edge, Kitase noted that while he wanted to keep story emphasis balanced across the cast, he found that Kefka was one of two characters whose importance in the story grew larger than originally intended when development began. Originally the game was meant to end much earlier with Kefka's defeat and the world saved, but when the developers realized they still had plenty of time, they added a second act where Kefka succeeds in devastating the world, leaving the party members scattered across the remains of the "World of Ruin".

Other developers involved with Final Fantasy VI's production also contributed to his characterization. Artist Kazuko Shibuya aimed to illustrate his "crazy and somewhat childish" demeanor through her work on his pixel art and animations, and considers him her favorite character in the franchise. While the rest of the cast had simple traits that were easy to draw, often easy to define as "cute" or "strong", she felt Kefka wouldn't stand out as much if he went through the same process. She utilized bases of red and green in his design to paint him as "very eccentric", while also wanting to illustrate his dangerous and childish aspects, a character with "no defined limits". Translator Ted Woolsey, who handled the North American localization of the game, also contributed lines to the character while working on the title, namely in part to get around Nintendo censors. Several of these have appeared in later interpretations of the character in other games, such as Kefka's statement about making "a monument to non-existence" in Final Fantasy XIV.

Kefka first appears as a general to Emperor Gestahl, serving as his court mage. Prior to the start of the game, he was the first human to be experimentally infused with the magic-like craft "Magitek", which granted him the ability to wield magic, although the imperfect process warped his mind and made him into the nihilistic psychopath he is during the course of the game. Through the first half of the game, Kefka leads the charge for the city-state of Vector to conquer the world, one kingdom at a time, using their magic weapons. Kefka mentally enslaves Terra and uses her to lead an attack on the town of Narshe to claim the frozen esper Tritoch there. When she escapes Imperial control, he pursues Terra to the kingdom of Figaro, setting the castle ablaze as she, Locke and King Edgar flee.

During a siege on the kingdom of Doma, Kefka grows impatient with fellow Imperial General Leo and poisons the drinking water in the castle of Doma, resulting in mass casualties and a swift victory for the Empire. After the alliance of Espers and revolutionaries invade and destroy Vector, Gestahl feigns sorrow for the Empire's evils, and to gain the trust of the protagonists, Gestahl has Kefka imprisoned, citing the poisoning of Doma. Kefka later goes to the village of Thamasa to kill the espers congregated there, killing Leo when he tries to intervene. Using the power of the espers, Kefka helps Gestahl raise the espers' homeworld to create the Floating Continent, where they intend to awaken three entities known as the Warring Triad. Upon being confronted by the protagonists, Gestahl freezes them except for former Imperial general Celes, whom he orders to kill her friends to show her loyalty to the Empire. However, she refuses and stabs Kefka instead, driving him into a psychotic rage. Kefka and the Emperor then get in a heated argument regarding the power of the triad—the Emperor only wants enough power to rule the world, while Kefka wants to unleash the Warring Triad's full potential. The Emperor tries and fails to kill Kefka, who retaliates by having the Warring Triad unleash their power to strike Gestahl down and unceremoniously boot him off the Floating Continent to his death. Kefka then moves the statues of the Warring Triad out of balance, unleashing enough raw magical energy to reshape the face of the planet, bringing about the second act of the game.