Theodore Maxtible was a human scientist and the father of Ruth Maxtible. He and Edward Waterfield experimented with time travel, bringing them in contact with the Daleks in 1866. He willingly served the Daleks, who promised him the secret of turning lead into gold. He felt no guilt at the deaths caused by the Daleks. He was eventually turned into a human Dalek and was last seen on Skaro running into the Dalek Emperor's throne room, proclaiming that the Daleks would "live and rule forever!". He was presumably killed in the destruction of the Dalek City. (TV: The Evil of the Daleks)
The Doctor later described Maxtible as "a greedy fool" to his companion Zoe Heriot. (PROSE: The Wheel of Ice)