The types of dragons in "Skyrim" are Regular, Blood, Frost, Elder and Ancient, plus Revered and Legendary dragons for high-level Dragonborn. Some quests involve skeletal dragons, but these encounters are scripted. Skeletal dragons do not appear in the wild.
The main character encounters different types of dragons based on level. Regular dragons begin to show up around level 10. Level 20 Dragonborn encounter Blood dragons, then Frost dragons at level 30. The dragon type generally changes every 10 levels, with the exception of Legendary dragons, who show up at level 75. Revered dragons breathe fire, while Frost dragons breath frost. Other dragon types do not have a fixed elemental breath. Using spells with the opposite elemental effect causes greater damage, but dragons resist 50 percent of damage from spells of the same element.
Besides the dragon types, the Dovahkiin encounters several named dragons. Alduin, Paarthurnax and Odahviing are named dragons essential to the main questline. Dragon names are usually made up of three one-syllable words from the dragon language. For example, the name Odaviing breaks down to od-ah-viing and translates to snow-hunter-wing. Some named dragons, such as Paarthurnax, do not have an associated dragon type, while others, like Viinturuth, have a dragon subtype as well as a name.