* CompleteMonster:
** [[BigBad The Second Cobra Commander]], real name [[FromNobodyToNightmare Krake]], is the egomanical psychopath who took over the terrorist organization Cobra after the previous leader's death. Growing up in a war-torn country, Krake became a [[SociopathicSoldier dangerous soldier]] by his teen years, and ruthlessly killed anyone who threatened his livelihood, from innocent slaves who worked too slowly, to his own partners when he suspected one of them might be a mole. Joining up with Cobra, Krake became one of its top enforcers, murdering dozens of innocents and trying to slaughter an entire village of people throughout his missions. Eventually taking over the organization as the new Commander, Krake's first order is to lead to an onslaught on the entire country of Nanzhao, massacring hundreds of innocents, nuking its major cities, and turning it into a radioactive wasteland. Showing no loyalty or care for anyone but himself, Krake regularly attempts mass murder and bombings, from shooting up airports and bombing entire cities, to [[ThereIsNoKillLikeOverkill trying to drop an entire plane onto the city of Paris to kill one person]]. With slave camps worldwide, Krake has adults and [[WouldHurtAChild children]] alike forced to work under threat of death, and, in some cases, sends the children to training camps where they are brainwashed into becoming sociopathic fanatics of Cobra's cause. A homicidal megalomaniac who killed any and all threats or annoyances to himself on a whim, Krake is one of the most wicked Cobra Commanders throughout the ''G.I. Joe'' franchise.
** [[ChaoticEvil Chimera]] is a former Green Beret who got rich from manipulating stocks, but when his crimes were discovered and his money taken from him, he [[PaterFamilicide murdered his entire family]] before going on the run. Undergoing facial reconstruction surgery, Chimera bombs the clinic where he had his operation to [[HeKnowsTooMuch kill anyone who saw his face]], and later [[CopKiller murders numerous police officers]] who try to arrest him. Taking over a gang of thugs after executing their current leader, Chimera kidnaps a governor's daughter, claiming his plans to use her for ransom to his gang, before sadistically murdering her in front of her father to show his true goal isn't money, but destruction. Chimera reveals he has set two timers, one of which will release a toxin that will kill millions of people worldwide, the other which will leak stock market strategies and money laundering secrets to corrupt individuals, and will lead to economic failure within a few years. Though killed while trying to murder numerous Joes, Chimera's money laundering secrets are still leaked online. [[ForTheEvulz Demented and sadistic]], [[ChaosIsEvil Chimera]] may have been one of the earlier major villains the Joes faced, but he was easily one of the worst.
** [[SadistTeacher Skull Buster]] is the recruit trainer for Cobra, and a [[DrillSergeantNasty sadistic brute]] to boot. To [[TrainingFromHell train potential recruits]], Skull Buster takes them on long treks through isolated locations such as deserts or jungles, forcing them to start out naked and starved. When any of the recruits show weakness, such as decreasing mental health or revulsion at eating raw meat, Skull Buster wastes no time in ruthlessly killing them. Along their travels, Skull Buster has his troops murder any and all people they come across, be they Taliban soldiers or innocent villagers-[[WouldHurtAChild inclusing children]]--in order to steal their supplies. Doing this routine weekly on separate groups each time, Skull Buster enjoys his job way too much, and takes {{sadist}}ic pleasure in any of his trainees' deaths, be they by his hand, their own weakness, or [[DrivenToSuicide suicide]]. Though having limited appearances, Skull Buster made his mark as the most wicked low-level villain in the story.
** ''Future Noir'': In this non-canon, alternate universe, [[MorallyAmbiguousDoctorate Dr. Mindbender]] is portrayed as far worse than his mainstream counterpart. A sociopathic MadScientist, Mindbender performs horrifying experiments on numerous innocents, [[WouldHurtAChild including children]], who are drawn into the cult of Cobra. These experiments [[BodyHorror leave them as hideous monsters in constant agony]] that he uses to kill anyone who defies Cobra. With [[PsychoSupporter raving fanaticism for his leader]], Serpentor, Mindbender plans to spread a toxin countrywide that will turn all it infects into [[AndIMustScream monstrous and mangled beasts]] in order to leave only the "pureness" of the Cobra cult to exist in the world. Commiting his crimes ForScience and {{misanthrop|e Supreme}}y, Mindbender stood out as a wicked monster who more than made up for the relatively low quantity his crimes with the sheer monstrosity of said crimes.