In recent years, bears have killed about one person annually in the U.S. and one in Canada. Black bears have caused about half of the fatalities, and the much larger brown bears killed the others. (Polar bears apparently have not killed any North Americans in this century -- yet.)
Lightning is much more dangerous, killing about 100 people in the U.S. and Canada each year. A North Carolina man is particularly unlucky, having been struck by lightning in 2006 and then attacked by a bear in 2010. On the other hand, perhaps he’s particularly lucky, since he survived both events.