Dragon
Dragon is creature type in Heroes of Might and Magic III. In Restoration of Erathia there are six different dragons:
Rampart has 
Green Dragons which can be upgraded into 
Gold Dragons.
Dungeon has 
Red Dragons which can be upgraded into 
Black Dragons.
Necropolis has 
Bone Dragons which can be upgraded into 
Ghost Dragons. Additionally, these are both undead creatures.
Armageddon's Blade expansion added four neutral dragons, which are also available in The Shadow of Death:
Armageddon's Blade expansion added also 
Vial of Dragon Blood artifact, which increases attack and defense of dragons by 5. Dragons also receive 5 attack and defense if they are fighting in the armies of Mutare, Mutare Drake, or the Overlord incarnation of Tarnum.
All living dragons, as well as 
Hydras and Chaos Hydras, 
Sea Serpents and Haspids 
and 
Couatls/Crimson Couatls , can be transformed into Bone Dragons at a Skeleton Transformer.
Troops under the effects of the 
Slayer spell receive additional attack when targeting dragons.
Dragons
Heroes with a specialty
Mutare the Overlord and
Mutare Drake the Overlord have dragons as a specialty. All dragons receive +5 Attack and +5 Defense.