Francis Klum also known as later Mysterio, Francis was the third to take the mantle and the only one who also had any actual powers. Francis was at first a crime and drug lord forced by his abusive brother into his life of crime in the beginning.
Francis Klum's ancestors were during World War II were experimented on by Nazis in an attempt to see if they could force and replicate the mutant gene to make a "Master Race". As a result while the mutant gene seemingly remained dormant for a couple generations in his family before awakening sometime in either the late twentieth or early twenty first century. As Francis Klum was growing up he was often a target for bullies both due to his meek appearance and being Jewish, his brother Garrison however would step in publicly to save him but would molest Francis while claiming Francis "owed" him for the protection. One night Garrison learned of his ability to teleport things into people by accidently teleporting mouth was into his own mother's heart killing her and leaving Francis with only Garrison to provide for them. Not long after Francis learned he had the ability to teleport things as well as telepathy after Garrison forced him to look at his mother's corpse at the funeral home. As the years went on Garrison would continue to molest Francis even as an adult and forced him to help in his drug trafficking by teleporting the drugs directly into the buyers system to eliminate telltale signs such as needle marks. As a result both became rich and took up legal businesses as well as a cover though Francis was still somewhat submissive to his older brother out of fear.
As Garrison became even more depraved due to targeting young women and teenage boys to rape and murder, Francis was quick to call his brother out on the extra risk but his brother would always ignore and threaten him. Eventually Francis grew sick of this abuse and when Garrison captured and planned to rape Black Cat before planning to murder her so Francis killed him by teleporting into Garrison's body before making his escape. After Black Cat was arrested due to the police believing her the killer of Garrison, Francis who felt some attachment to her, teleported her to a bridge to talk. There he revealed the fact of how his brother raped him for so long and how it messed with him to the point he once raped a prostitute when she mocked him. After admitting this he seems to hold some regret but feared prison but he couldn't see her imprisoned for his crimes, Black Cat tried to reason with him that if he revealed what his brother has done to him he would be shown some sympathy along with potentially mercy. Francis admits he fears no one understands him and will just mock him only for Black Cat to admit that she was once raped and that she would support him. As Francis starts to consider it he is brutally beaten by Spider-Man, both from PTSD as this was the bridge Gwen Stacy died on and believing Francis was attacking her, believing Black Cat set him up Francis pulls out a gun and tries to shoot them only for Spider-Man to jam the gun causing Francis to fall off the bridge leaving everyone to believe him dead. In truth Francis was able to teleport to safety but due to the kinetic force he had gathered from when he was falling he lost one leg upon impact and left disfigured. Seeking revenge Francis decided to spend ten million dollars to buy one of the original Mysterio's old costumes from Kingpin so that Spider-Man wouldn't be prepared for someone with actual powers.
Francis as Mysterio decided to attack a High School to after Spider-Man revealed his secret identity but he was thrown off by two other Mysterio's appearing, one a seemingly undead Quentin Beck and the second an angry Daniel Berkhart, Berkhart feeling that Francis was undeserving of the mantle of Mysterio faced him in hand to hand combat to which Francis wasn't able to win as due to wanting to keep his powers hidden from Spider-Man thus refused to use them against Berkhart. As soon as Francis could he snuck around the building and nearly killed Spider-Man by having him slit his own throat but ultimately stopped by Flash Thompson who knocked the knife away. Attempting to flee with a hostage as leverage Francis tries to take the school nurse, Miss Arrow, hostage only for her to impale him with a spike from her arm. Wounded and desperate he teleported away but later to revealed to of died as those spikes killed anyone who wasn't Spider-Man or similar.
At some point he is revived through cloning by Jackal II in an attempt to find a way to conquer death. Feeling indebted he decided to work with this Jackal as a means to both get revenge and to survive as despite being resurrected by the cloning the process was still flawed to where the bodies required pill to hold off the cellular degeneration so he is forced by this Jackal to hold off on his revenge and assist him in finding ways to cheat death, however he is quickly killed off when Doctor Octopus betrayed this Jackal and activated a wave that accelerated the degeneration process killing Francis and most the other clones.
Before his disfigurement Francis was a man of average height, appeared to be somewhat thin, brown hair and a somewhat large nose with a pair of glasses. While the exact extent of his disfigurement is hard to tell due to the fact he were bandages it seems it was fairly bad and as Mysterio he looked identical to the others. After being revived while never shown out of his costume it is likely he no longer had his disfigurements.
Francis Klum is a man who will stop at nothing to get revenge on those who have hurt him and to get what he desires in life namely monetary gain. He is also shown both pragmatic and a man with some standards as he reveals he hates rape, even when he did apparently rape the prostitute it is portrayed as something he wasn't proud of and seemingly a one time act he regretted. To further emphasize this he admits this was due to the trauma of what his brother did to him to which the prostitute mocked though he does admit he knows what she went through. Francis is a deeply traumatized man that given the life time of abuse to the point he never felt a genuine bond with another human until Black Cat when she showed some sympathy, this however faded after he believed she was just trying to kill him.
That said he was uncertain if the wanted to kill Black Cat or not despite making it clear he wanted to kill Spider-Man who he seemed to blame the most for his recent misfortunes. He also seems to have some regret for killing his brother due to believing they set him up to kill Garrison as he mentions he planned to avenge him as well despite making it clear he hated what Garrison did to him. When revived he was willing to work with the man who resurrected him in his plot to find a way to cheat death to avoid dying a second death and working on ways to stabilize his new body.
Francis Klum on his own even before obtaining the Mysterio suit was able to teleport both himself and any material anywhere he can think of, this included drugs to which he could do both safely or fatal depending on the amount, telekinesis to an unknown degree and he could also cause an individual to suffer realistic hallucinations by manipulating their perceptions of reality to force them into doing things they never would willingly do. Upon gaining the Mysterio suit he could produce similar special effects to the others through devices, shoot some minor energy blasts as well as hiding both his prosthetic leg and disfigurements from the general public.
Francis Klum is by far the most sympathetic of any Mysterio in the comic and media as whole due to the disturbing sexual abuse he suffered which is rarely covered in Spider-Man stories and not too common for Marvel.