Skeletal Dragons

Skeletal 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).

Description
These undead dragons wield strong magic and attack anyone daring too 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 skeletal dragons are found in the Ultima series, both in dungeons on Serpent Isle in Ultima VII Part Two.

Trivia

 * Lorthondo raised a skeletal dragon.