ostracizer
/ˈɒstrəˌsaɪzər/Definitions
1. noun
A person who ostracizes others, especially as a form of punishment or social exclusion.
“The politician was ostracized by her peers and became an ostracizer in the community.”
2. verb
To exclude or banish someone from a group or community, often as a form of punishment or social exclusion.
“The club ostracized the new member for not following the rules.”