Rasputin (?.)

• Svengali
• access
• bad influence
• big wheel
• court
• eminence grise
• five-percenter
• friend at court
• good influence
• gray eminence
• heavyweight
• hidden hand
• influence
• influence peddler
• influencer
• ingroup
• key
• kingmaker
• lobby
• lobbyist
• lords of creation
• man of influence
• manipulator
• open sesame
• powers that be
• pressure group
• sinister influence
• special interests
• special-interest group
• the Establishment
• very important person
• wheeler-dealer
• wire-puller