Best fixer ever was Recoil. My first GM came up with him. Recoil was an ork. He was really more of an arms dealer than a fixer. He had a van full of guns. You asked him what he had, and he looked around in the back of the van. Like a taco truck, but for guns. If you had extra money, he might find a gun that he was planning to sell to someone else, and you could make that person wait. I shamelessly stole Recoil for my games.
I'm currently using an Elf fixer named Gunner. He is an independent, originally from Vladivostok. He travelled as a gunner on panzer crews for about a decade, making friends everywhere he went. When the panzer rigger got killed, Gunner was stranded. After a few weeks he realized his main source of income was putting his friends in touch with each other or moving other people's loot for a percentage, so he made the jump to Fixer. He speaks several languages, knows a ton of smugglers, a few other fixers, several Johnsons, and loads of mechanics and arms dealers.