ruiner
Definitions
A person or thing that causes the destruction, downfall, or decay of something.
Someone who spoils or brings to ruin the prospects, reputation, or happiness of another.
Examples
The sudden rainstorm was the absolute ruiner of our outdoor wedding plans.
He has a reputation as a party ruiner because he always brings up depressing topics.
The unexpected plot twist was a total ruiner for the suspense of the entire movie.
Synonyms
destroyer wrecker spoiler devastator saboteur ravager underminer