Teddy Baxter

 was a comedian in 1956. Steven Taylor encountered him after exiting the TARDIS and became his straight man in the comedy act. As well as being a comedian he was also an amateur astronomer and discovered the "tenth" moon of Jupiter shortly before his original stage partner had disappeared. He was the key to why the First Doctor and The Doctor's TARDIS went missing. He had discovered the Vardan's Mediasphere and they wanted to kill him for seeing the sphere as part of their plans. As they showed him his future they created a Fixed point in time. He helped to stop the Vardan's plans. (AUDIO: The Vardan Invasion of Mirth)