How would you make an npc go around an object?

I understand some things about pathfinding, but really only about making a character move from one place to another. Like from point A to point B. A---------B However, I would like my NPC to not go in a straight line but in a zigzag pattern to it's location. (I'm making a defense game were you have to fight off a horde of zombies. The zombies would go around buildings to you base.) So for example, a zombie would move from point A around object X to point B. __ A------'X'--------B

I've tried doing this using bricks that would bring a zombie to a location on touched, but this is inefficient and I was wondering if there is a simpler way to do this.