COPYCAT
copycat, imitator, emulator, ape, aper
(noun) someone who copies the words or behavior of another
Source: WordNet® 3.1
Etymology
Noun
copycat (plural copycats)
(informal, derogatory) One who imitates or plagiarizes others' work.
A criminal who imitates the crimes of another; specifically, a criminal who commits the same crime, especially a highly-publicized one, that has just been or recently committed by someone else.
Adjective
copycat (comparative more copycat, superlative most copycat)
Imitative; unoriginal.
Verb
copycat (third-person singular simple present copycats, present participle copycatting, simple past and past participle copycatted)
To act as a copycat; to copy in a shameless or derivative way
Source: Wiktionary