"I killed a man named 'Smith' with a bottle because I am an evil human being. ...Isn't that enough?"The Ace Attorney franchise has produced its fair share of monstrous villains:
—The real killer (spoiler), Apollo Justice: Ace Attorney, Episode 4: "Turnabout Succession"
- Manfred von Karma is the Big Bad of the first game. As a prosecutor, he had a flawless, decades-long win streak, until defense attorney Gregory Edgeworth managed to have him penalized for his illegal workings in the courtroom, causing von Karma to become enraged by the black mark on his previously-perfect record. Right after the end of the case, an earthquake hit the building. It trapped Gregory Edgeworth, his nine-year-old son Miles, and a bailiff inside an elevator. As oxygen was beginning to run out, the bailiff panicked and attacked Gregory. Miles threw a piece of evidence from the trial at them to get them to stop fighting, which turned out to be a gun, which fired once, a terrible scream was heard, and then Miles passed out from lack of oxygen. Von Karma had come across them. The bullet from the gun shot through the glass and hit his shoulder, causing him to scream. For revenge, von Karma picked up the gun and shot the unconscious Gregory in the heart. Afterwards, von Karma took Miles under his wing and, for fifteen years, raised Miles to be the antithesis of everything that Gregory Edgeworth was, twisting the boy to fit his views and become a ruthless, cold-hearted prosecutor who cared for nothing but getting a guilty verdict every time. Finally, on the very last day before the Gregory Edgeworth murder case was closed forever, von Karma set up a murder and pinned the blame on Miles Edgeworth, intending to have his own foster-son executed for a murder he didn't commit. Von Karma also planned it out so that Miles would be convinced that he himself was the one who had killed his father and would confess to and be charged with that murder as well.
- Matt Engarde from the second game threw away his loving and devoted manager Celeste Inpax once he was done using her to further his career. When Celeste was engaged to his rival, Engarde told him Celeste was “used goods” to trick him into calling off the wedding. Celeste killed herself, to Engarde's delight. Engarde later hired professional assassin Shelley de Killer to murder his rival, but kept blackmail material to betray de Killer as well. To force Phoenix Wright to acquit him for murder, Engarde had de Killer kidnap the innocent Maya Fey and attempted to pin his crimes on the innocent, miserable and insecure Adrian Andrews partly for the thrill of hurting her.
- Dahlia Hawthorne, the Big Bad of the third game, previously manipulated her boyfriend into assisting her in a crime, before framing him for murder and ensuring his suicide to cover her tracks. She later poisoned the lover of the prosecutor Mia Fey when he got too close to her crimes, before she seduced Phoenix Wright as well. When her twin sister Iris fell for Phoenix, Dahlia accelerated her plans to poison him. When an ex-lover of hers tried to warn Phoenix, Dahlia murdered him and tried to frame Phoenix. Despite being executed, Dahlia returned as a vengeful ghost, aiding her mother to kill Dahlia's cousin Maya Fey solely to spite her elder sister Mia's spirit. Taking steps to manipulate her twin again to help with the murder, she came back from the dead to possess Misty Fey—albeit due to Misty's desire to protect her niece Pearl—and attempted to murder Maya, being stopped only by the intervention of Godot who killed her host. But despite this she became convinced that she had forced Maya to murder her own mother and caused her to commit suicide, which she gloated over to their faces. She's also a giant hypocrite, as she shows nothing but disgust towards Morgan Fey because of the "petty revenge" that she was after, but at the same time was going along with Morgan's plan specifically in order to get her own revenge on Mia.
- Kristoph Gavin is introduced as a supposedly helpful mentor. He is also the first man responsible for ushering in “The Dark Age Of The Law” by getting Phoenix Wright disbarred. Kristoph ended up taking a massive blow to his ego when a magician and prospective client, Zak, rejected Kristoph as his lawyer. When Zak hired Phoenix instead of him due to a poker game, a furious Kristoph decided to get revenge. He had gotten a shy artist named Vera to unknowingly create fake evidence for the trial, but after Phoenix was hired, Kristoph used the evidence to get him disbarred. Kristoph also manipulated his own brother, prosecutor Klavier, by using him to disbar Phoenix and cheating the honorable Klavier out of a fair trial. Klavier, who knew something wasn't right, was haunted for years. When Zak resurfaced under a new identity years later, Kristoph took the chance to murder him and frame Phoenix. After this, it was revealed Kristoph had poisoned Vera and her father Drew, intending both to die. Vera survived, barely. To pour salt on the wound, Kristoph gloated how Apollo and Phoenix had triggered his plan-their questioning caused Vera to bite her nails- when he had planted the poison as nail polish, knowing her nervous habit. He had even started poisoning her when she was only twelve. After her survival, Kristoph simply enjoyed seeing Vera face conviction for her own father's murder. In the end, he was little but a cruel, petty, selfish man obsessed with glory and destroying those who stood in his way.
- While initially seeming like a frail and kind individual, Big Bad Quercus Alba turns out to be the hardened, cold-hearted boss of a large and powerful smuggling ring. Thanks to him putting many highly-convincing counterfeit bills into circulation, the country of Zheng Fa has been thrown into economic chaos due to his machinations. He also ordered the deaths of Cece Yew, Deid Mann, and Byrne Faraday due to their efforts in trying to expose his role in the smuggling ring, and personally murdered Mask*DeMasque II and his subordinate Manny Coachen: DeMasque II for stealing the fake statue that contained the plates used for creating counterfeit bills, and Coachen due to him seeking to steal power of the smuggling ring from under Alba's nose. Ruthless and rotten to the core, Alba will kill anyone without so much as a second thought for the sake of keeping his criminal empire running.
- The spy known as the phantom is the Big Bad, extremely nasty and is the second figure, after Kristoph Gavin, who ushered in "The Dark Age Of The Law." He started off by disguising himself with a mask he found and killing Athena Cykes's mother when Athena was only 11 years old, in front of her no less, and ended up getting Prosecutor Blackquill convicted. He also sabotages a national symbol of pride, the HAT-1 rocket, almost killing the astronaut on board. Six years later, he likely killed the real Detective Bobby Fulbright and assumed his identity in order to be Simon's handler. He also killed Apollo's best friend since junior high, Clay Terran, because Clay almost revealed his identity. He has ruined the lives of several people besides the aforementioned Athena Cykes and Prosecutor Simon Blackquill and is indirectly responsible for almost every murder in the game, including setting off the bomb in the courtroom that was thought to be the work of Ted Tonate, which could have caused massive amount of death. Oh, and he framed two girls, Athena and her best friend, an Ill Girl; the aforementioned Prosecutor Blackquill; and an astronaut for his crimes. To top it all off, if one counts the murder done by his associate, Ted Tonate, he has the highest death toll of the entire franchise. What's really disturbing is that nobody knows his true identity and he doesn't feel emotions the same way "normal" people do. Because of this, he is a chillingly realistic version of a Sociopath in a video game.