Matthew Finnegan

Matthew Finnegan was a companion of the Tenth Doctor who ultimately became the Tef'Aree.

Travels with the Doctor
Matthew originally worked for a film studio in 1920s Hollywood. (COMIC: Silver Scream, Fugitive)

During his first adventure aboard the Doctor's TARDIS, Matthew found himself overshadowed by fellow companion Emily Winter. This seemed to displease him. He was easily manipulated by the Advocate into betraying the Doctor. The reason he gave was that he was protecting Emily and he was terrified of dying like Adric (whom he learned about from what was supposedly Vislor Turlough's journal). When the Doctor discovered this, he was furious with Matthew and they parted company. Matthew told the Doctor he trusted the Advocate more than him, so he would travel with her for a while. The Doctor was appalled by Matthew's behaviour, but still threatened the Advocate should she harm Matthew. (COMIC: Tesseract)

Martha Jones refers to him as suffering from Tin-Dog-Syndrome just as Mickey Smith did.

Rebirth
Matthew spent the next two years of his life with the Advocate, not realising he was a mere slave. Emily found him, slapped him for his betrayal and told him that Turlough had confirmed he never kept a diary. Matthew felt very guilty for what he had done to the Doctor and Emily. They joined forces against the Advocate. When Matthew sacrificed himself to save a race from annihilation, killing the Advocate, their energies combined and Matthew was filled with fifth-dimensional energy. He was reborn as the Tef-Afree, the first and only fifth-dimensional being, despite the death of his original human body. No longer an entity bound by linear time, he became present at all the Universe's history.

To ensure his rebirth as the Tef'Aree, Matthew manipulated events leading to his creation. He allowed the Advocate to reform from spacedust, diverted an Anochian ship to 16th century Greenwich, saved Emily Winter, gave the humans of Colony One terraforming and teleport technology and showed Leo Miller how to travel to 1920s Hollywood. He appeared after his 'death' to the Doctor to confirm all this. He was chastised for his manipulation of sentient beings, among his past self, just to ensure his own creation. The Doctor turned away from Matthew forever in disgust. The Tef'Aree reminded the Doctor that he was Matthew, despite his protests to the contrary and left, saying they would meet again. (COMIC: Final Sacrifice)