Tallan was a Time Lord in an alternate version of Gallifrey. He was on the High Council and lead the inauguration of Leela as Lady President. (AUDIO: Reborn)
K9 Mark II created a Matrix projection of this Time Lord to bring Romana back to her version of Gallifrey. He did this as he couldn't create a projection of himself in the Matrix because he was a machine. (AUDIO: Ascension)