Belial is a character from -

Belial, fictional character, a fallen angel in John Milton’s Paradise Lost (in 10 books, 1667; in 12 books, 1674) who tries to persuade the others to be more discreet so that their unacceptable behaviour is less conspicuous. The Hebrew word bĕlīyaʾal, apparently with the literal meaning “worthlessness,” was used in Old Testament epithets for the wicked and impious, such as the “sons of Belial.” In later traditions it was taken as a proper name, a byname for Satan.
Source: Britannica