To blacken thoroughly; to make very black.

Fig.: To blacken or sully; to defame.

charge falsely or with malicious intent; attack the good name and reputation of someone; "The journalists have defamed me!" "The article in the paper sullied my reputation"

Denigrate is a heavy metal band from Tuusula, Finland, formed in 1996.

belittle; "Don't belittle his influence"

to put down (someone's ethnicity, background, etc.)