Machiavellian

Concise Oxford English Dictionary © 2008 Oxford University Press:
Machiavellian /ˌmakɪəˈvɛlɪən/

▶adjective cunning, scheming, and unscrupulous, especially in politics. ▶noun (also Machiavelli) a Machiavellian person.

– derivatives
Machiavellianism noun.

– origin from the name of the Italian statesman and writer Niccolò Machiavelli, whose work The Prince (1532) advises that the acquisition and use of power may necessitate unethical methods.