marrer
One who blemishes
A marrer is something that mars or spoils—a blemish, defect, or source of damage: The only marrer of the evening was his late arrival.
The word is rare, formed from the verb mar plus the agent suffix -er.
Most speakers would choose flaw, defect, or spoiler instead.
ruiner
One who destroys
saboteur · vandal · destroyer · tarnisher · disruptor · corrupter · despoiler · defiler · impairment · detriment
blemish
Visible flaw or mark
- defectInherent imperfection or fault
- imperfectionFault or shortcoming
- disfigurementMarred physical appearance
scar · blot · stain · mark · fault · flaw · taint · smudge · scratch · nick