Murmur is a villain from the DC comics and media.
Murmur was originally a surgeon who went insane. He went on a killing spree, believing it would stop the voices in his head. Later, he was sentenced to death by lethal injection; a procedure that failed due to his abnormal bloodstream. Whilst in jail, he cut out his own tongue and sewed his mouth shut in order to stop himself from confessing to any crimes.
Murmur appears as an episodic villain in Episode 16 of Season 3 of Arrow, and later returned as an ally of Damien Darhk. In the series his origins are way different,instead of being a psychotic doctor, he was a thief beaten by cops during an interview. Giving a false confession, he sew his mouth out of rage.