you can, just be sure to cite or source them in someway shape or form.
Pesonally, i would use this:
Template gotten from [http://en.wikipedia.org/wiki/Template:Navbox] on October 26th, 2010.
It tells people 1) where i got it from, 2) when i got it (in the case the original page receives an update that my page doesn't have), and 3) if i were to choose to provide little to no documentation, the link tells people where to go for more details on how to use the template.