noun
A somewhat literary or dramatic term for a violent criminal, ruffian, or assassin. Often used in news reports or fiction to describe a dangerous perpetrator.
凶漢が深夜の街を徘徊していた。
A villain was prowling the streets late at night.
警察は凶漢の行方を追っている。
The police are tracking the outlaw's whereabouts.
悪党 is a more general and colloquial term for a villain or scoundrel, while 凶漢 carries a stronger nuance of violent criminality and is more literary.
殺し屋 specifically means a hitman or professional killer, whereas 凶漢 can refer to any violent criminal, including an assassin, but is not limited to hired killers.
Compound of 凶 (bad, evil) and 漢 (man, fellow). The exact historical derivation is uncertain, but the word has been used since at least the Edo period to denote a violent or wicked man.