Razorback is a species that is partly pig, partly boar and partly human. There are two kinds of Razorback. A form that looks like a standing pig with tusks and other one that looks like a standing boar with tusks and black fur.
Razorbacks are mobs who will always stay at the same spot. When you are 5 levels higher or lower, they will not attack you anymore.
A summary of all the Boars in the game: Category:Razorback.