The Sixth Doctor (Colin Baker)

The Sixth Doctor is the name given to the sixth incarnation of the fictional character known as the Doctor, seen on screen in the long-running BBC television science-fiction series Doctor Who.

He was portrayed by actor Colin Baker, and a cameo by Sylvester McCoy underneath a curly wig during the Sixth Doctor's regeneration scene into the Seventh where McCoy's face is not even seen unblocked as the Sixth Doctor.

This technically makes the Sixth Doctor one of only two incarnations of the Doctor to have been officially played by more than one actor, the other being the First Doctor.

Within the series' narrative, the Doctor is a centuries-old Time Lord alien from the planet Gallifrey who travels in time and space in his TARDIS, frequently with companions.

When the Doctor is critically injured, he can regenerate his body; in doing so, his physical appearance and personality change.

Although his televisual time on the series was comparatively brief and turbulent, Baker has gone on to find consistent critical acclaim as the Sixth Doctor in Big Finish's range of original Doctor Who audio adventures.

The Sixth Doctor's brightly coloured, mismatched clothes and brash, overbearing personality set him apart from all his previous incarnations, in some ways hearkening back to the early irascibility and undertones of untrustworthiness of the First Doctor.

The Sixth Doctor appeared in three seasons; however, in his first outing in Season 21 he appeared only in the final episode of The Caves of Androzani which featured the regeneration from the Fifth Doctor and thereafter in the following serial The Twin Dilemma to end that season.

The Sixth Doctor's era is noted for the decision of the BBC controller Michael Grade to put the series on an 18-month hiatus between seasons 22 and 23, with only one new Doctor Who story, Slipback, made on radio during the hiatus, broadcast as 6 parts (at 10 minutes each) on BBC Radio 4 from 25 July to 8 August 1985, as part of a children's magazine show called Pirate Radio Four.

He also appeared in the special Dimensions in Time. There are also novels and audio plays featuring the Sixth Doctor. A glimpse of a sketch of the Sixth Doctor was later seen in John Smith's A Journal of Impossible Things in the revived third series episode "Human Nature". A brief holographic clip of the Sixth Doctor appears in "The Next Doctor".