Sophia (The Secret History)

 was a human/Hetrodon hybrid and a time sensitive. She was employed by the Monk to help him in his plans to get revenge on the Eighth Doctor after he caused Tamsin Drew's death. She told Vicki Pallister that Steven Taylor was taken to Constantinople. The Monk took her from Greece. She released some flying stone head which attacked Justinian. (AUDIO: The Secret History) The Monk used her powers to divert the Seventh Doctor to take the place of the Third Doctor battling the Europans on Delphin Isle. (AUDIO: The Defectors) Then on the Sixth Doctor taking him to a Cyberman base in the Keiper Belt replacing the Second Doctor. (AUDIO: Last of the Cybermen) Finally to move the Fifth Doctor to Constantinople in the 5th century replacing the First Doctor. Here this action allowed the Monk to replace the Doctor in his timeline. (AUDIO: The Secret History)