Meddler (noun)

A person who interferes in the affairs of others without invitation or permission.

Origin:

From meddle, which means to interfere in something that does not concern you.

Examples:

1. His sister was a meddler, always sticking her nose into his personal affairs.
2. The politicians were accused of being meddlers, trying to influence the outcome of the election.
3. The meddler was always trying to give unsolicited advice and never minding her own business.
4. The company was accused of being a meddler in the affairs of other companies, through unfair competition practices.
5. The neighbor was a notorious meddler, always trying to know everyone's business and gossiping about it.