Mine would be Bill Gates. I swear if you modeled a Johnson after that man he would be the ultimate Johnson. He would have you go on a run, and then betray you. If you live from being betrayed he would just incorporate you into his corporate structure by blackmailing you then eventually disposing of you when he saw fit.
Mr. G: "We are moving towards synergy in the upwards revenue stream dynamics to create a positive condensing flow aura."
Shadowrunner: "What the drek does that even mean?" *shadowrunner takes a bullet to the brainpan splattering blood over the wall.*
"It means your worth more dead to me then alive." says Mr. G (and his glasses have to reflect in that odd way like that crazy killer in SIN CITY)
If Gates was in shadowrun I could see him implanting cranial bombs discreetly into every single person he would hire. You would never even know it either. He would probably find your street doc contact and pay him a wad of cash to install it with your new set of skillwires or whatever. The next time he wants you dead your head pops open like a pinyatta spraying brain confetti everywhere.