I need to make spiked hair for a fondant figure I'm putting on a cake. What would be the best way to do this?

A fondant figure? That means small
Roll tiney balls of fondant into tear drops w/the tops being stringey?
Pipe it w/icing after on cake using a small round tip?
Cover a wedge of fondant w/tip 3 or 14 pulled up stars?

This is a technique I've used when making small figures from clay, but I don't see why it wouldn't work with fondant: use q-tips. Nice firm ones, not the loose and soft ones. I have some cosmetics ones with pointed ends that I think would work marvelously. Because they're smaller than your fingers, you can manipulate smaller areas with them. And then I would just pinch the spikey hair out.

....who are you doing the figure of, out of curiosity? Because when you say spikey hair, I immediately think of a video game character...

Or . . . squeeze the fondant through a garlic press and cut off sections as you go. Of course it depends on how big the figure's head is going to be.

Give him "normal" fondant hair, then with the point of small scissors (like cuticle scissors) snip a whole bunch of little cuts into the hair and use a tootpick to raise up the points, if necessary.