Ood Elder
The Ood Elder was the leader of the ruling council on the Ood Sphere in 4226, identifiable by the external forebrain. When the mind of the Ood became plagued by nightmares, the Elder sent Ood Sigma to send a telepathic message to the Doctor, very shortly after the events on Bowie Base One in 2059, to bring him to the Ood Sphere. (DW: The Waters of Mars)
When the Doctor arrived, the Elder and the other Ood that were present showed him a vision of the Master. Despite the Master's death and refusal to regenerate after the Year That Never Was cancelled itself out. He also showed The Doctor images of Wilfred Mott, sitting at a table, looking upset, and of Joshua Naismith, in the mansion. The Doctor then left, returning to 21st century Earth to stop the Master.
He, along with the other Ood, telepathically sang with the Doctor as he died. (DW: The End of Time)