Ood Elder

The Ood Elder was the leader of the ruling council on the Ood Sphere in 4226. 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, this warned the Doctor that the Master had returned. The Doctor then left, returning to 21st century Earth to stop the Master. (DW: The End of Time)

He has a larger brain than other Ood.