Shiva created this monster during his quarrel with Daksha, after hearing that his wife Sati had died. Shiva was so saddened by her death that he tore out his hair in grief. The hair then became Virabhadra, whom Shiva then commanded to destroy Daksha. Having done this, Shiva reabsorbed Virabhadra to become Hare, the ravisher. Based on an illustration found at http://www.exoticindiaart.com/product/PB56/ Virabhadra had four arms and wore both a lot of gold and a handlebar mustache. Other than the four arms and the fact that everything above the shoulders appears to be on fire, the monster looks almost human. Of course, calling Virabhadra a monster is a bit misleading, since he doesn't appear to be a monster in the sense that, say, your standard Hydra or Chimaera would be. He is often pictured conferring grace on one or another lesser divinity or mortal and has a really nice temple in Lepakshi, a substantial change from the tearing-around-the-countryside-eating-virgins type monsters we tend to favor in the west. Virabhadra was also the leader of a group called the Ganas.
Sources: http://sadasiva.com/M_SIVA/va26.html, http://www.jivamuktiyoga.com/focus/archive_pgs/0402.html, www.adindia.net/virabadra.htm