The antagonist of Victor Hugo's novel "Les
Miserables". He is an obsessive, merciless police inspector who doggedly chases the novel's protagonist for many years. Javert committs suicide by throwing himself into a river when he cannot reconcile his strict belief in the law with his new found sense of mercy.
As a noun, Javert refers to a person of similar
characteristics: ruthless, obsessive,
perfectionist. It may also refer to a television trope (or cliche), describing a character that fills a similar role of the actual Javert from Hugo's novel.
Javert may also be used as a verb, referring to the act of relentlessly chasing someone or something.