Kefka (he is Cefca Palazzo in the Japanese version) is the main antagonist of the game. One of the most notorious of all the Final Fantasy villains; he isn’t a living incarnation of sin, or a supreme god-like being come to plunge the world into utter darkness. He is just an evil, evil man; one part coward, one part clown, one part mage, and one part nihilistic megalomaniac bent on world domination. His infamous cackle is one of the first things verbally spoken in a Final Fantasy game.
Kefka was born and immediately abandoned. He was raised in a Thamasa orphanage in which he was beaten often by the orphanage head. He developed a cold, quiet personality due to his early experiences. Kefka eventually migrated to Vector and entered the Imperial academy where he graduated at the top of his class. Cid immediately recognized his talents and took him on as an apprentice, putting him in prime position to be the first volunteer for the Magitek Knight program. He was genetically fused with magic through an imperfected program, but for years showed no signs of it affecting his sanity whatsoever. He went on to become incredibly successful within the Empire, taking command of the Magitek Knights at only 23 years of age. It was then that he met Celes Chere, an orphaned citizen of Tzen, and took a liking to her.
Celes became his apprentice and he pulled several strings to ensure that she became a Magitek Knight herself. Kefka's imperial career peaked at age 31 when he was made Imperial Prime Minister, a position second only to Emperor Gestahl himself. Kefka gained fame as a brilliant tactician and strategic savant. It was at this time that Kefka's sanity began to deteriorate, most likely due to imperfections in the original magic-infusing process he underwent from Cid. At a banquet celebrating Celes' promotion to Rear Admiral, Kefka finally cracked with a violent outburst, and slid quickly into insanity afterwards. Once shy and taciturn, Kefka began dressing in garish clown costumes and wearing makeup. Memories of his teenage and adult life began to fade away, leaving only his horrid childhood. Thus he became more cruel and more hateful and eventually developed a bloodlust and an obsession with destruction.
Gestahl noticed this and removed him from the military. However, Gestahl was still thankful to Kefka for his years of service beyond expectation and stellar military record, so Kefka was placed at the position of Court Mage. His former position was filled by General Leo, which sparked Kefka's intense jealousy and hatred of the man which culminates during the events of the game. Kefka's reputation among imperial soldiers is on display in the camp outside Doma castle during Sabin's scenario. He has a reputation as a coward, yet many of the imperial soldiers still fear him due to his being prone to wild fits of rage and violence.
Kefka is responsible for many of the game's events. He is the one who demands that a Slave Crown be put on Terra's head. He also is responsible for the poisoning of Doma's water supply; after General Leo takes too long to formulate an attack plan, Kefka decides to take matters into his own hands and poisons the water. He is also at the Magitek Research Facility, where he physically and mentally abuses Espers to suck them dry of their power. In a ploy later in the game, Emperor Gestahl puts Kefka in prison, claiming that his poisoning of Doma was unnecessary and cruel. After it is revealed to be an evil Imperial plot, Kefka comes to Thamasa where he turns the congregated Espers into Magicite.
Using that power, Kefka and Emperor Gestahl revive the Floating Continent, where statues that keep the world in balance reside. After the party reaches him, he freezes them all (except Celes) with power that he is getting from the statues. He then orders her to stab the party, and gives her a sword. Refusing, she stabs him instead. Kefka is annoyed and enraged, but not fatally wounded. He orders the statues to kill them all. Gestahl, afraid that Kefka is going to upset the gentle balance of the statues, shouts at him to stop. Kefka refuses, leading Gestahl to try to kill him. However, he discovers that Kefka is shielded by the power of the Statues, rendering magic thrown at him completely null. Kefka then kills Gestahl and merely kicks his body off the edge of the Floating Continent. Shadow moves all of the statues around, trapping Kefka on the Island, but reshaping the World of Balance into the World of Ruin.
In the World of Ruin, Kefka is technically the "god" of the land. He rules with an iron fist from atop his perch in Kefka's Tower. If so little as one person opposes him, he destroys their entire town with the "Light of Judgment." The effects of this are seen in several places, especially in Tzen and Mobliz. Followers of his have joined a cult called the Cult of Kefka. Members walk around mindlessly, and one villager says that there is no hope for them. However, Strago is seen with them, and he can be revived.
After reaching the top of Kefka's Tower, Kefka can't believe that the party can have so much hope in such a ruined world. They all use examples from their personal lives (and quests in the game). This angers Kefka, and he takes on his god form, which has several stages with multiple forms in each stage. After defeating him, the end of magic in the world is witnessed. Terra, being part Esper, was believed to be one of the casualties at first, but then she lands on the airship, alive and well.
Kefka owes his name to nihilistic writer Franz Kafka, an allusion to Kefka's nihilistic motives.
Kefka along with Sephiroth from Final Fantasy VII are the 2 most memorable villains in Final Fantasy history, and are two of the villains that are mentioned from the start of the storyline and make constant appearances. Interestingly, they have a lot of similarities in their final boss battles. Both take angelic-like god forms and they even share an attack, specifically Heartless Angel.