THE SILENT MAJORITY.

МОЛЧАЛИВОЕ БОЛЬШИНСТВО

Explanation: 

The large number of people who do not express their opinions publicly.

I suppose these ideas represent the opinion of the silent majority.

THE (MEN IN) GREY SUITS.

ЛЮДИ В СЕРЫХ КОСТЮМАХ.

Explanation:

People in business or politics with a lot of influence or power, although they are not well known to the public.

The men in grey suits are very influential and powerful nowadays, although many people don't know them.

NEW KID ON THE BLOCK.

НОВИЧОК, НОВЕНЬКАЯ 

Explanation: 

Someone who is new in a place or organisation and has many things to learn about it (informal).

John has been working in the company for 7 days and feels like a new kid on the blocks.