Detractor (noun)

1. A person who finds fault with or denigrates something or someone.
2. A person who lessens the value, importance, or reputation of something or someone.

Origin:

From latin detractor ("one who takes away"), from detrahere ("to take away"), from de- ("away") + trahere ("to draw").

Examples:

1. The politician had many detractors who criticized her policies.
2. The new restaurant had a few detractors who did not like the food.
3. The movie was a hit with audiences but had its fair share of detractors.
4. She had a lot of detractors in the office who were jealous of her success.
5. He is known as a detractor of the current government policies.