plagiarist       
noun [ C ] uk/ˈpleɪ.dʒər.ɪst/ us/ˈpleɪ.dʒɚ.ɪst/
 剽窃者
a person who uses another person's ideas or work and pretends that it is their own
  The reporter was shown to be a liar and a plagiarist. 该记者被证明是个说谎者和剽窃者。 
 The self-confessed plagiarist admits that his new novel borrows from his own past work "hugely".
 See: plagiarize
 - More examples
 - The paper unmasked one of its reporters as a serial plagiarist and fraud.
 - Although the man is a plagiarist, he is not a deliberate plagiarist.
 - Plagiarists are not clever or they'd be doing their own work.