faultfinder

[ fawlt-fahyn-der ]

/ ˈfɔltˌfaɪn dər /

a person who habitually finds fault, complains, or objects, especially in a petty way.

Origin of faultfinder

First recorded in 1555–65; fault + finder

I want to know what the fault-finder lays to your charge, what solemn admonition has called up the roses on those fair cheeks!

The Haunted Room |A. L. O. E.
A critic is not a fault-finder, necessarily; you are very plain.

Tessa Wadsworth's Discipline |Jennie M. Drinkwater
Find faulte is rather a loss: it is better than 'fault-finder.'

Elizabethan and Jacobean Pamphlets |Various
That is the one the fault-finder said produced such deep depression of feeling.

The Poet at the Breakfast Table |Oliver Wendell Holmes, Sr.

"I'm afraid you're a bit of a fault-finder," said Mrs. Hatchard, shaking her head at him.

Sailor's Knots (Entire Collection) |W.W. Jacobs