The Spenserian villain most likely to remind you of a horror movie, Malegar is one creepy dude. Alive, but lacking any blood and therefore nearly impossible to injure, Malegar is kind of like your proto-zombie. He and his crew attack the tranquil house of Alma in Book 2 and represent the threat of lawlessness, not only through their chaotic and unprovoked attack, but also through their un-dead state, which defy the laws of nature as well.
Since Alma is a figure who represents the well-balanced body, it make sense that Malegar and his totally weird body would be her enemy. It also makes sense that both Arthur and Guyon eventually defeat him, by squeezing instead of hacking the life out of him, since they represent proper leadership and temperance respectively.