Don’t forget the majordomo. 
You could hire Scylla, he’s got plenty of experience.
Don’t forget henchmen! You’ll need plenty of extra henchmen, because (of course) you will casually execute any that displease you. There is no need to tolerate bumbling, after all.
Marcus Licinius Crassus was the richest Roman of his time(Later Republic). He is reputed to have said that no man could call himself rich unless he could equip and field an army.
He was the guy played by Sir Laurence Olivier in Spartacus. As hot as he looked then I would have done him if he was penniless!
I will need the following
Accountants + staff*
Lawyers + staff
Chief of security + personal bodyguards
Public relations agent
Several stockbrokers/financial advisors
2 Trusted lieutenants (one male, one female)
Evil henchmen
Hired goons
Pilot + crew
Driver
“Entertainment” officer
Weather machine operaator
Laser repairman
Butlers
Groundskeepers
Martial arts instructor
Weapons master
Geneticly enhanced mutant creature wrangler
Scientists
and so on
- Some of these you may want to outsource as the need arises
Well, if I were really a zillionaire, I’d probably hire a few of those people. I eat badly and am in bad shape, so I’d get a good cook and a personal trainer. I probably couldn’t resist hiring a housekeeper just to come in once a week- don’t fancy the idea of a full-time housekeeper wandering around my house, though. I wouldn’t bother with a driver. I would get a style consultant/personal shopper to help me look good. And a masseuse to come by from time to time.
I guess I’d need a trustworthy accountant, if I was a zillionaire.
Don’t all true zillionaires have at least one cabaña boy? At least that’s one of the luxuries I would HAVE to have. 
Since you’ll probably need to make occasional public appearances, decoy assassins away from you, etc., you need a squad of look-alikes.
And “bodyguards” for the look-alikes… whose REAL job is to kill the look-alike if he starts to make you look bad or supplant you.
Anybody else keep thinking of the cartoon with
“I am Elmer J. Fudd, Millionare. I own a Mansion and a Yacht.”
“Again!”
“I am Elmer J. Fudd, Millionare. I own a Mansion and a Yacht.”
“Again!”
And fluffers. If you’re gonna have concubines, you gotta have fluffers!
What about an orchestra? If I’m making any public appearances I’d like my own custom fanfare played whenever I enter and exit a room, or say something brilliant. Come on, how cool would it be to have something like the Imperial March play everywhere you went. And if some young plucky hero ever attacks my fortress of doom, we’ll need some battle music for the confrontations with my league of ninja body guards.
Don’t forget the guy who’d let you beat him up. whenever you felt angry. You’d have to pay extra to have him go without padding, but I think the money’s worth it.
The scary thing is…for the right money, you’d really find no shortage of people who’d be willing to take that job.
And, if you really wanted to go “all out,” you could buy a private island, or a large stretch of land hidden deep within the Amazon, and therein release your enemies that you’ve had kidnapped, so you could hunt them like animals for sport.
So, you’d need enough guards, suave international kidnappers, gunsmiths, big-game hunter coaches, hunting-camp staff, and native Levis to make that work. Plus, a Taxidermist who could be trusted to keep quiet when you bring back your “trophies.”
Hell, there’s all kinds of fun you could have with the “Force others to fight to the death” angle. Like secret gladiatorial games, for instance. Or hiring ex-Soviet fighter to dogfight each other (with live ammo) in old MiGs over international waters.