1) Controversialist 2) Disputant 3) Eristic 4) Finger pointer 5) Finger-pointer 6) Litigant 7) Namer of names 8) One faced in court 9) One making charges 10) One pointing a finger 11) One with a pointed finger 12) Person imputing blame 13) Plaintiff 14) Plaintiff, usually 15) Pointer of the finger 16) Whistle-blower 
• (n.) One who accuses; one who brings a charge of crime or fault.
Ac·cus'er noun [ Middle English acuser , accusour ; confer Old French acuseor , from Latin accusator , from accusare .] One who accuses; one who brings a charge of crime or fault. 
[n] - someone who imputes guilt or blame
noun someone who imputes guilt or blame
a person who accuses, esp. in a court of law: a trial in which the accuser and accused may freely speak.