copycat
🇺🇸
/ˈkɑːpikæt/
🇬🇧
/ˈkɒpikæt/
A person who imitates others, especially in a way that is annoying.
Billy is always a copycat, following what his friends do without any original ideas.
Describing something that is done in imitation of something else, especially in a way that is not original.
The news reported a series of copycat crimes that followed the high-profile case.