Warning: The following text contains spoilers relating to the plot of Prophecies.
Glint is a Dragon of ancient age - nearly 3000 years old. She is a prophet and an oracle, making prophecies about the future of Tyria. In the mission Dragon's Lair, the players seek an audience at Glint and she recognizes them as the Chosen, foreseen to save Tyria. Her lair is said to be inside a single grain of sand in the vast Crystal Desert.
Glint was the first creature made by the Gods of Tyria. She was to be the caretaker of Tyria but was later on aided by the Forgotten. She shows a concern for the fate of humans and aids players with advice and visions of what is taking place. She also enlists their aid in defeating the Titans in the Titan Quests.
The bonus for the Dragon's Lair mission is to defeat Glint in battle. This has no effect on relationships with Glint in the game. If your party is defeated she spares your lives and sends you on your way. Even if you slay her (and she is a formidable foe), you will encounter her in later parts of the game. Strategies to defeat Glint can be found here.
A monument of Glint can be found in the Salt Flats.
A shrine for Glint can be found in Droknar's Forge, guarded by the Brotherhood of the Dragon. At this shrine players can summon the Vision of Glint (her avatar) to communicate with her and receive the final quests of the campaign.
Warning: The following text contains spoilers relating to the plot of Eye of the North.