The Dawnguard Add-on for The Elder Scrolls V: Skyrim has 10 achievements worth 250 gamerscore.
Defeat a Legendary Dragon
Complete "Kindred Judgment"
Complete "Beyond Death"
Complete "Awakening"
Complete "Lost to the Ages"
Learn all three words of Soul Tear
Use the special power of Auriel's Bow
Acquire 11 werewolf perks
Acquire 11 vampire perks
Change your face