maligner vs backbiter

maligner and backbiter both are nouns.

Word	Noun	Adjective	Verb	Adverb
maligner	Yes	No	No	No
backbiter	Yes	No	No	No

As nouns, maligner and backbiter are synonyms defined as:

maligner and backbiter: one who attacks the reputation of another by slander or libel

Other synonyms of maligner include defamer, libeler, slanderer, traducer, vilifier.

maligner (noun)	backbiter (noun)
one who attacks the reputation of another by slander or libel	one who attacks the reputation of another by slander or libel