Quest callbacks are made by using the function RegisterQuestEvent(QuestId, EventId, Function).
QUEST_EVENT_ON_ACCEPT = 1 --(pPlayer, QuestId)
QUEST_EVENT_ON_COMPLETE = 2 --(pPlayer, QuestId)
QUEST_EVENT_ON_CANCEL = 3 --(pPlayer)
QUEST_EVENT_GAMEOBJECT_ACTIVATE = 4 --(GameObjectId, pPlayer, QuestId)
QUEST_EVENT_ON_CREATURE_KILL = 5 --(CreatureId, pPlayer, QuestId)
QUEST_EVENT_ON_EXPLORE_AREA = 6 --(AreaTriggerId, pPlayer, QuestId)
QUEST_EVENT_ON_PLAYER_ITEMPICKUP = 7 --(ItemId, Count, pPlayer, QuestId)
[edit]Creature Events

Creature callbacks are made by using the function RegisterUnitEvent(CreatureId, EventId, Function).
CREATURE_EVENT_ON_ENTER_COMBAT = 1 --(pCreature, event, pAttacker)
CREATURE_EVENT_ON_LEAVE_COMBAT = 2 --(pCreature, event, pLastTarget)
CREATURE_EVENT_ON_TARGET_DIED = 3 --(pCreature, event, pDied)
CREATURE_EVENT_ON_DIED = 4 --(pCreature, event, pLastTarget)
CREATURE_EVENT_ON_TARGET_PARRIED = 5 --(pCreature, event, pTarget)
CREATURE_EVENT_ON_TARGET_DODGED = 6 --(pCreature, event, pTarget)
CREATURE_EVENT_ON_TARGET_BLOCKED = 7 --(pCreature, event, pTarget, pAmount)
CREATURE_EVENT_ON_TARGET_CRIT_HIT = 8 --(pCreature, event, pTarget, pAmount)
CREATURE_EVENT_ON_PARRY = 9 --(pCreature, event, pTarget)
CREATURE_EVENT_ON_DODGED = 10 --(pCreature, event, pTarget)
CREATURE_EVENT_ON_BLOCKED = 11 --(pCreature, event, pTarget, pAmount)
CREATURE_EVENT_ON_CRIT_HIT = 12 --(pCreature, event, pTarget, pAmount)
CREATURE_EVENT_ON_HIT = 13 --(pCreature, event, pTarget, pAmount)
CREATURE_EVENT_ON_ASSIST_TARGET_DIED = 14 --(pCreature, event, pAssistTarget)
CREATURE_EVENT_ON_FEAR = 15 --(pCreature, event, pTarget, pSpell)
CREATURE_EVENT_ON_FLEE = 16 --(pCreature, event, pTarget)
CREATURE_EVENT_ON_CALL_FOR_HELP = 17 --(pCreature, event)
CREATURE_EVENT_ON_LOAD = 18 --(pCreature, event)
CREATURE_EVENT_ON_REACH_WP = 19 --(pCreature, event, pWaypointId, pForwards)
CREATURE_EVENT_ON_LOOT_TAKEN = 20 --(pCreature, event, pPlayer, pItemId)
CREATURE_EVENT_ON_AIUPDATE = 21 --(pCreature, event)
CREATURE_EVENT_ON_EMOTE = 22 --(pCreature, event, pPlayer, pEmote)
CREATURE_EVENT_ON_DAMAGE_TAKEN = 23 --(pCreature, event, pAttacker, pAmount)
[edit]GameObject Events

GameObject callbacks are made by using the function RegisterGameObjectEvent(GameObjectId, EventId, Function)
GAMEOBJECT_EVENT_ON_CREATE = 1 --(pGameObject)
GAMEOBJECT_EVENT_ON_SPAWN = 2 --(pGameObject)
GAMEOBJECT_EVENT_ON_LOOT_TAKEN = 3 --(pGameObject, event, pLooter, ItemId)
GAMEOBJECT_EVENT_ON_USE = 4 --(pGameObject, event, pPlayer)
GAMEOBJECT_EVENT_AIUPDATE = 5 --(pGameObject)
GAMEOBJECT_EVENT_ON_DESPAWN = 6 -- No arguments passed.
[edit]Gossip Events

Gossip Event callbacks can be made using any of the following functions. Note that the pUnit in the arguments of these functions variate depending on the register you use.
RegisterUnitGossipEvent(UnitId, EventId, Function) (Applies to Creatures only)
RegisterGOGossipEvent(GameObjectId, EventId, Function)
RegisterItemGossipEvent(ItemId, EventId, Function)
GOSSIP_EVENT_ON_TALK = 1 --(pUnit, event, pPlayer)
GOSSIP_EVENT_ON_SELECT_OPTION = 2 --(pUnit, event, pPlayer, id, intid, code)
GOSSIP_EVENT_ON_END = 3 --(pUnit, event)
[edit]Server Hooks

Server Hook callsbacks can be made by using the RegisterServerHook(EventId, Function) method.
SERVER_HOOK_NEW_CHARACTER = 1 --(event, pName, pRace, pClass)
SERVER_HOOK_KILL_PLAYER = 2 --(event, pPlayer, pKiller)
SERVER_HOOK_FIRST_ENTER_WORLD = 3 --(event, pPlayer)
SERVER_HOOK_ENTER_WORLD = 4 --(event, pPlayer)
SERVER_HOOK_GUILD_JOIN = 5 --(event, pPlayer, pGuildName)
SERVER_HOOK_DEATH = 6 --(event, pPlayer)
SERVER_HOOK_REPOP = 7 --(event, pPlayer)
SERVER_HOOK_EMOTE = 8 --(event, pPlayer, pUnit, EmoteId)
SERVER_HOOK_ENTER_COMBAT = 9 --(event, pPlayer, pTarget)
SERVER_HOOK_CAST_SPELL = 10 --(event, pPlayer, SpellId, pSpellObject)
SERVER_HOOK_TICK = 11 -- No arguments passed.
SERVER_HOOK_LOGOUT_REQUEST = 12 --(event, pPlayer)
SERVER_HOOK_LOGOUT = 13 --(event, pPlayer)
SERVER_HOOK_QUEST_ACCEPT = 14 --(event, pPlayer, QuestId, pQuestGiver)
SERVER_HOOK_ZONE = 15 --(event, pPlayer, ZoneId, OldZoneId)
SERVER_HOOK_CHAT = 16 --(event, pPlayer, pMessage, pType, pLanguage, pMisc)
SERVER_HOOK_LOOT = 17 --(event, pPlayer, pTarget, Money, ItemId)
SERVER_HOOK_GUILD_CREATE = 18 --(event, pPlayer, pGuildName)
SERVER_HOOK_ENTER_WORLD_2 = 19 --(event, pPlayer)
SERVER_HOOK_CHARACTER_CREATE = 20 --(event, pPlayer)
SERVER_HOOK_QUEST_CANCELLED = 21 --(event, pPlayer, QuestId)
SERVER_HOOK_QUEST_FINISHED = 22 --(event, pPlayer, QuestId, pQuestGiver)
SERVER_HOOK_HONORABLE_KILL = 23 --(event, pPlayer, pKilled)
SERVER_HOOK_ARENA_FINISH = 24 --(event, pPlayer, pTeamName, bWinner, bRated)
SERVER_HOOK_OBJECTLOOT = 25 --(event, pPlayer, pTarget, Money, ItemId)
SERVER_HOOK_AREATRIGGER = 26 --(event, pPlayer, AreaTriggerId)
SERVER_HOOK_POST_LEVELUP = 27 --(event, pPlayer)
SERVER_HOOK_PRE_DIE = 28 --(event, pKilled, pDied)
SERVER_HOOK_ADVANCE_SKILLLINE = 29 --(event, pPlayer, SkillId, SkillLevel)
SERVER_HOOK_DUEL_FINISHED = 30 --(event, pWinner, pLoser)
SERVER_HOOK_AURA_REMOVED = 31 --(event, pAuraObject)
SERVER_HOOK_RESURRECT = 32 --(event, pPlayer)