Consigliere

A consigliere is an advisor, especially one who serves as a trusted counselor to a powerful figure.

The term comes from Italian and entered English primarily through depictions of the Mafia, where the consigliere advises the boss on strategy and mediates disputes: He served as consigliere to the family for thirty years.

Outside organized crime contexts, it describes any close, influential advisor: She became his political consigliere during the campaign.