Kamelion

Kamelion was a shape-changing android. Used by the Master to impersonate King John, he later travelled as a companion to Fifth Doctor. (DW: The King's Demons) This continued until his destruction, having again fallen under the influence of the Master. (DW: Planet of Fire)

However, this would not be the end for him. He gained and lost a new host body, (PDA: The Ultimate Treasure) had a child with the Doctor's TARDIS (ST: The Reproductive Cycle) and used his mental link with the Doctor to allow the Master to trap the Doctor within a dreamscape. (BFA: Circular Time)

Creation
Kamelion was the creation of the Gelsandorans. (PDA: The Ultimate Treasure) He was the tool of an invader of the planet Xeriphas. When the Master was trapped on that planet, he discovered Kamelion and used him in his next encounter with the Doctor. Although Kamelion was sentient to a degree, he was extremely weak-willed, and open to manipulation by any strong personality. (DW: The King's Demons)

Travels with the Fifth Doctor
The Doctor freed Kamelion from the Master's control, and he joined the Doctor in the TARDIS. (DW: The King's Demons)

Kamelion preferred to remain in the TARDIS for fear of being taken over by a stronger personality and used against the Doctor. (MA: The Crystal Bucephalus) However, he did help to rescue the Doctor and Turlough during a trip to the Moon with a Victorian lunar expedition in 1878; initially confined to the TARDIS by a force field preserving an atmosphere on a lunar park, Kamelion was later able to leave the park and rescue the Doctor as he died of asphyxiation on the surface. Later, he helped the Doctor and Turlough salvage weapons to use against the ruthless Vrall. (PDA: Imperial Moon)

Kamelion eventually fell under the Master's remote influence in Lanzarote and assumed the shape of Peri's loathed stepfather, Howard Foster, and then the Master himself. In the end, Kamelion begged the Doctor to end his life. The Doctor reluctantly honoured that request. (DW: Planet of Fire)

Afterlife
A little of Kamelion's personality survived as a result of his interfacing with the TARDIS. When the ship arrived on Gelsandor, the natives gave him a new body, only for him to sacrifice himself to save the Fifth Doctor and Peri. (PDA: The Ultimate Treasure)

Later, Kamelion and the TARDIS had a child together, which was raised by the Sixth Doctor and Peri Brown. It developed into a double of Peri and took her place on Earth while the real Peri travelled with the Doctor. (ST: The Reproductive Cycle)

As the Fifth Doctor lay dying from spectrox toxaemia, enough of Kamelion's mental link to him existed to allow the Master to use Kamelion to trap the Doctor in a dreamscape within his own mind, slowly destroying his will to regenerate. Thanks to the encouragement of Nyssa, also mentally linked with him, the Doctor was able to see through the illusion. Freed from the Master's control once again, the psychically linked aspect of Kamelion in the Doctor's mind was able to join Nyssa and the Doctor's other companions from across space and time to free him from the trap so he could regenerate. (BFA: Circular Time)

Other information

 * Kamelion assumed the shapes of John of England, Tegan Jovanka (DW: The King's Demons), Howard Foster, the Fifth Doctor, and the Master. (DW: Planet of Fire)


 * While dying from the effects of spectrox toxaemia, the Fifth Doctor hallucinated about many individuals including Kamelion, urging him to live. (DW: The Caves of Androzani)

Behind the scenes

 * According to the featurette Kamelion - Metal Man, included on the DVD release of The King's Demons, the robot used for Kamelion was not custom-made for the series, but was a device discovered by producer John Nathan-Turner when he was searching for a possible successor to K9. According to the featurette, script editor Eric Saward and Peter Davison, were extremely skeptical that the robot would work as an ongoing companion due to its frequent malfunctions.
 * Kamelion's mouth was designed to move in sync with the pre-recorded dialogue by Gerald Flood.
 * Kamelion only appeared twice in the series; further appearances were impractical due to the special effects required. A scene involving Kamelion was filmed for The Awakening but was cut before transmission. As a result there are no references to Kamelion in any episodes between The King's Demons and Planet of Fire, not even in The Five Doctors, which occurs immediately after the events of Kamelion's debut.
 * According to Peter Davison in the Metal Man featurette, any sign of regret shown by him/The Doctor during Kamelion's "death" scene was pure acting. He was in reality gleeful to be done with the troublesome prop.
 * A box set containing The King's Demons and Planet of Fire was released under the title Kamelion Tales.