Rezh Baphix
Chorister Rezh Baphix was the last Chorister of Akhaten. Much like all Choristers, he was a servant of the Mummy. He sang the Long Song along with Merry Galel while in the pyramid. The unending song ended with him when the Mummy awoke, after Merry stumbled on a verse of the song and quit singing.
When the Eleventh Doctor and Clara Oswald entered the pyramid to save him and Merry, he was frantically continuing the Long Song, hoping the Mummy would not awake. The Doctor informed him that the Mummy would wake up even if he kept singing, and the Long Song would have to end with him so he could escape harm. Baffix stopped singing and teleported from the pyramid to save himself. (TV: The Rings of Akhaten)