From Longman Dictionary of Contemporary Englishdo-gooderdo-good‧er /duː ˈɡʊdə $ -ər/ noun [countable] HELPsomeone who helps people who are in bad situations, but who is annoying because their help is not needed – used to show disapproval I’ve got very little time for those interfering do-gooders.
Examples from the Corpus
do-gooder• Pearson isn't just a do-gooder - he's been in prison and wants to help others stay out.• Louise was a do-gooder, and you could never predict who would show up at her house.• One is a social activist with a high moral tone, an earnest do-gooder and role model to millions.• While southern church folk ranted about the invasion of do-gooders, they raved about black roles in Reconstruction.• Nor can the Republican majority on his panel be viewed as simply do-gooders out to restore candor to the White House.• The do-gooders suddenly found themselves in the role of trying to tell the Abs what was good for them. 