Someone Machiavellian is sneaky, cunning, and lacking a moral code. The word comes from the Italian philosopher Niccolò Machiavelli, who wrote the political treatise The Prince in the 1500s, that encourages “the end justifies the means” behavior, especially among politicians.
When a person is called a Machiavellian, it means that they're so focused on their own interests and desires to the point they would hurt others to achieve those needs.