Solaire of Astora

Solaire of Astora is a character in Dark Souls. He is voiced by Daniel Flynn, who also voiced Vamos and the Giant Blacksmith.

Plot
Solaire is first found just in front of the bridge that leads to Undead Parish, gazing at the sun. Speaking to him here will give the player the White Sign Soapstone and allow him to be summoned to fight the Belfry Gargoyles. Solaire spawns only after the Taurus Demon is killed.

After meeting Solaire in Anor Londo and defeating Ornstein and Smough, Solaire will move from Anor Londo to the Sunlight Altar, offering the player a chance to join the Covenant of Sunlight.

Solaire may be summoned for the fight with the Gaping Dragon in the Depths.

After defeating the Centipede Demon and entering the Demon Ruins, the player will encounter him again. If the player speaks to Solaire immediately after OR takes the most obvious route to the next area, Solaire will become hostile while taking a secret route and attack the player on their next meeting.

If the player instead takes the shortcut to Izalith (which can only be accessed through being a +2 Chaos Servant), and destroys all nine of the Chaos Bugs found there, Solaire will remain lucid and can be summoned for the fight against Gwyn.

Lore
Knight Solaire of Astora is a Knight bound to a quest of finding his own "sun", for which he became undead.

Strategy
It is ill-advised to kill Solaire until the player is forced to, as killing him will make him unavailable for future boss fights. However, should the player wish to attack him, Solaire will fight with a sword and shield, and use the Lightning Spear miracle.

Trivia

 * Solaire is referenced in an Easter Egg in the game Borderlands 2, where a mock bonfire can be found with an armored man named "Solitaire" sitting next to it.