Calymath, the son of the Turkish Sultan, is the leader of the Turkish army that first demands the tribute from Ferneze and later invades Malta. Even though the Turks (a.k.a. the Ottoman Empire) were the Big Bad Wolf of Renaissance geopolitics, Calymath doesn't come off as all that bad a guy. While Ferneze and Barabas align themselves with Machiavelli, Calymath is the guy who opts for leniency and comes through on his promises. Let's take a look:
When Ferneze first begs him for a month to rustle up the money for the tribute, Calymath gives it to him, saying "'tis more kingly to obtain by peace/ Than to enforce conditions by constraint" (1.2.25-6). And later, Calymath agrees to make Barabas Governor of Malta if Barabas gets the Turkish army into the city.
Once the army has taken control of Malta, Calymath actually honors the agreement. And then he does one better by throwing in a few janizeries (kind of the Turkish version of a soldier-cum-ninja) as a thank-you gift.
But this play is way too cynical to let the good guy win. Calymath expects Barabas and Ferneze to play by the same rules he does, so obviously he just ends up as Ferneze's captive after Barabas has blown up his entire army. We have to ask: who ends up being the more effective ruler—the guy who sticks to his moral guns, or the one who's willing to play dirty?