NBA teams need an "enforcer": that player that has the will and ability to make sure that you never ever take a cheap shot at their star player. They don't have to be star players, but they generally have to be big enough to be imposing.
There are a few of these players on the market.
Foster might not have been the most intimidating player, but he demonstrated that while his NBA career might be coming to an end in the near future, he could follow up in the future with a WWE career.
That's a pretty good flying elbow drop on the skull of Luol Deng.
Foster is "only" 6'11" and 236 pounds, but when all of that is coming down on one of those wrasslin' moves, it probably hurts like the dickens. Foster could find a job somewhere, even if it's just as an enforcer.
Evans, on the other hand, might have a job in ballet, as in the Nutcracker Suite. I know players are supposed box out, but I'm not sure what you call this move. It would give "Ball Night!" a whole new meaning on PTI.
Evans is an absolute gorilla. He's only 6'8" but is conservatively listed at 265 pounds. Most of that weight is in his chest nowadays. Teams could double using him for exercises making players run around his roughly quarter mile circumference.
Thomas might be the league's oldest player, but don't mess with him; he'll rough you up. That's Dennis Rodman he's manhandling there. And if you think he's gotten nicer in his old age, think again.
He might be the nicest guy in the world to his teammates, but he's downright MMA to the rest of the league.
Gray is another guy I like in this role. At seven feet, he is an absolute brick-house. Royal Ivey actually looks like he's trying to fake like he's flopping when he got sent down for reals here.
I haven't seen Gray in the enforcer role in the past, but he definitely has the size and strength to back it up.
Diop is another player like Gray. He doesn't have a history of hard fouls, but if he decided to invent one he'd be terrifying. At 7' tall and a full 300 pounds, the man is an absolute beast.
If none of those guys work out, or you just need to have "a word" with the ref, you can always see if this guy (45 second mark) is available form overseas.