There are several Michaels in the Bible, but the only important one is the archangel (meaning a sort of “ruling angel,” head over other angels).
The prophet Daniel mentions him more than once as a “prince,” a sort of heavenly protector of Israel (Dan. 10:13, 21; 12:1).
The book of Revelation pictures a conflict at the end of time, with Michael and his angels fighting against the dragon, Satan (12:7).
Michael is only one of two angels with names in the Bible, the other being Gabriel.