Onigawara, literally " Demon/Ogre/Goblin Tiles" can be found primarily on temple roofs, but also in shrines and residences. They serve as protection against the weather at the end of ridges.
They also function to ward off evil. What fascinates me in particular is the diversity. These first two are at Jyoei-ji, the temple in Yamaguchi that is home to a garden by Sesshu.
The Oni designs seem to date from the Kamakura Period. Prior to that these end tiles were decorated with flowers or animals. This one is from another temple in Yamaguchi, Toshun-ji.
They are almost always ceramic, though some were wood or stone. This one was at a former samurai residence in Chofu, Yamaguchi.
Many shrines and temples will display onigawara from older buildings that have been replaced like at this small rural shrine in southern Hiroshima.
A previous post on some Onigawara in Shikoku.