Given that no animal skulls are flat and perpindicular on all sides facing a shooter at the time of a shot, you can glance rounds off the skulls. This can be for bear, deer, hog, and even beaver....just about any of them, really.
I placed a .308 FMJ dead center of the top of the skull when the little boar had its head down toward me while feeding in my food plot. The shot was 85 yards. Unrealized by me, he was canted off to the side and my dead center shot skittered laterally to the boar's right. As you can see from the images, it damaged the outer table, damaged the inner table, but did not actually enter the brain cavity.
This next shot just forward of the ear (note 2 holes, the one in the ear 'lobe' was because the ear was down and forward at the point of impact) should have taken out the lower front portion of the brain case. It was with a .45-70 at just 35 yards. However, due to the downward and canted trajectory, the round actually completely missed damaging any of the skull or manible, but did traverse the neck apparently just beneath the foramen magnum and like the above pig, was DRT.