Crowbar is an American sludge metal band formed in New Orleans, Louisiana, in 1990. The band is fronted by vocalist/guitarist Kirk Windstein, Crowbar's sole constant member. Through infusing a slow, low-keyed, brooding doom metal sound with the aggression of hardcore punk, they pioneered a style known as sludge metal – albeit Windstein admitted a mild dislike to the term – alongside other bands of the New Orleans heavy metal scene such as Eyehategod, Soilent Green, Acid Bath, and Down.

Source: Wikipedia (https://en.wikipedia.org/wiki/Crowbar_(American_band))