Sahasrahla is a Hylian mage in the Zelda series that debuted in The Legend of Zelda: A Link to the Past. Sahasrahla is usually depicted as the elder of Kakariko Village who is reknown for his great magic.
Fallen Hero Timeline
The Legend of Zelda: A Link to the Past
In The Legend of Zelda: A Link to the Past, Sahasrahla is a descendant of the Sages that sealed Ganon in the Sacred Realm after his victory against the Hero of Time. Those were retroactively given the identity of the Sages awaken by Link in The Legend of Zelda: Ocarina of Time but in A Link to the Past, they are nameless wise men. This is the source of the old mage's powers in this game.
Sahasrahla is aware of Agahnim and his plans of gathering descendants of the Sages so he lives Kokoriko and hides near the Eastern Palace, which is where Link encounters him after learning of his whereabouts from Sahasrahla's Grandson. he then tells Link of the Pendants of virtues needed to draw the Master Sword from his pedestal and tells him that the Pendant of Courage is found in the eastern Palace itself. When Link shows him the pendant, Sahasrahla tells him that it is told that a hero is said to appear from the bloodline of those who guarded the Pendant, the Knights of Hyrule. Believing Link to be said hero, Sahasrahla entrusts him with the Pegasus Boots, which had been passed down by the families of the Seven Sages.
He then ask Link to retrieve the other pendants and help him by giving him advices for the rest of the game via telepathy. He usually communicate with him via Telepathy Tiles, which can be found at various place in Hyrule and the Dark World. He returns to his home in Kakariko after Ganon's defeat.
The Legend of Zelda: A Link Between Worlds
When Link meets Sahasrahla for the first time at his home in Kakariko, he tells him of Ganon's attempt to destroy Hyrule a long time ago, which refers to the events of A Link to the Past. After learning that Seres was turned into a painting by a man named Yuga, he is afraid that yuga is trying to revive Ganon as Seres is a descendant of the sage. He sends Link out to find his disciple, Osfala in the Eastern palace as he feels that he too is a potential target as a descendantt of the Sages.
Link fails and Osfala is captured, Sahasrahla meets Link outside of the Eastern Palace and learn of Ostafala's capture but they are interupted by an earthquake comming from Hyrule Castle. The two heads there to find a magical barrier created by Yuga. Sahasrahla laments over the fact that the Master Sword would be the only thing able to pierce the barrier and that the Pendant of Courage is inside the castle but Link soon reveal that Zelda gave it to him before he went to the eastern Palace. Sahasrahla tells him where the two others are and returns to his home in Kakariko waiting for Link to find them.
After Link obtains both remaining Pendants of Virtue, Sahasrahla speaks to him via telepathy, telling the young hero that he is now worthy of wielding the Master Sword, which is hidden in the Lost Woods. Once Link obtains the Master Sword, Sahasrahla will telepathically speak to Link, telling him to use the newly-obtained Sword to destroy the Barrier at Hyrule Castle. Sahasrahla then heads to Hyrule Castle, where he is waiting for the hero. Once Link destroys the Barrier, Sahasrahla expresses surprise at how easily the Master Sword cut through the dark magic.
After returning from Lorule via the crack near Link's House, he tells him about how cracks leading to Lorule have appeared everywhere after Yuga fused with Ganon. He then tells Link that a fissure appeared behind his house and can use that to reach a new part of Lorule.
His relation to the A Link to the Past Sahasrahla is unknown but he mentions at one point that his "grandfather's grandfather's grandfather" was around at the time, which may imply that the original Sahasrahla is his ancestor making him another descendant of the Sages and probably distantly related to Osfala as both the later and the A Link to the Past Sahasrahla seems to be descendants of Rauru, the Hylian Sage of light as Osfala is the Sage of Light and both Hylian share similar design with Rauru.