complainer

he's a chronic complainer, always finding fault with everything.

don't be a complainer; try to focus on the positive aspects.

the team needs a solution, not a constant complainer.

she's a notorious complainer about the food at restaurants.

we have a resident complainer in every department, it seems.

being a complainer won't solve the problem; action will.

he's such a complainer; it's exhausting to be around him.

the manager warned him not to be a complainer at work.

she's a relentless complainer, never satisfied with anything.

avoid being a complainer and try to offer constructive feedback.

the constant complainer drained the team's morale.