Skeletal Dragons

Skeleton dragons were once dragons that became so powerful in life, that they chose to live on even after their death (much in the way liches do). They wield strong magic and attack anyone daring to come close to their lair. Since they are only made of bones, however, strong blunt weapons such as hammers can smash them to pieces -- assuming a cunning warrior manages to come near enough in the first place...

Only two skeleton dragons are found in the Ultima series, both in dungeons on Serpent Isle in Ultima VII Part Two.

Trivia

 * Lorthondo raised a skeleton dragon.