**Depends on the size of the bear.** 

Black bears vary in size, small female bears can weigh in under 100 lbs, which makes them about the same size as a large dog. But big black bears can weigh in at more than 600 lbs. The largest black bear on record was in New Brunswick in Canada, and is estimated to have weighed ~1,100 lbs! 

A swat to the head by a bear of sufficient mass will undoubtedly be enough to end you life, as sure as a baseball bat to the head can kill you. Keep in mind that a seemingly innocuous hit to the head can be fatal to humans.

The strike force of a bear should not be underestimated. Grizzly bears for example have allegedly been recorded on multiple occasions—although occurrences are still very rare—decapitating moose with one swipe to the head *(moose have since been discovered to have a peculiar weakness in their necks that make them prone to decapitation)*. A large Black Bear is about the same size as an average Grizzly, so it's not unreasonable to assume a big enough black bear could potentially take your head off if it landed a well placed swat your cranium, although you'd more than likely be sent flying with your head still attached.