A is for... Alpha Centauri

A delegate of the Galactic Federation from the system of Alpha Centauri - its actual name is never revealed. It was sent to the planet Peladon as part of a wider delegation to assess its suitability to join the Federation. The Doctor described it as an hermaphrodite hexapod. It does have six arms, but walks like a slug or snail on one large foot. The mouth isn't visible, the head being a gigantic eye-ball. It speaks in a shrill feminine voice, and is a rather timid creature. It is also a bit of a jobsworth, unwilling to go against strict Federation policy, and lacks imagination. Its Martian colleagues, for instance, are prepared to bend the rules in order to help the Doctor and salvage the situation on Peladon. It is easily cowed into agreeing to make a vote unanimous.

When the Third Doctor returned to the planet some 50 years after his first visit, he was pleased to find that Alpha Centauri was still there - now an ambassador. It remembered him, and so helped smooth relations with the Peladonians. It was still quite timid, and a stickler for policy and procedure. The engineer Eckersley exploited this to get it to summon Federation troops to arrive - really his renegade Ice Warrior allies. Alpha Centauri formed a bond with Sarah Jane Smith, and did show some degree of bravery on this occasion, even prepared to go against its nature to assist with some subterfuge.

The longevity of the species is considerable. When the Twelfth Doctor had to contact nearby the nearest alien race to assist in the evacuation of Mars, it was Alpha Centauri who responded. This was in 1881.

Played by Ysanne Churchman (voice) and Stuart Fell (body). Appearances: The Curse of Peladon (1972), The Monster of Peladon (1974), and Empress of Mars (2017).

• The main difference in design between Alpha Centauri's two appearances is the cloak, as you can see above. It is a rather thin, ragged form in the first story, but has a more quilted "curtain" look for the second. Sadly the designer of the DVD covers did not spot this, and uses the Monster version on the cover of Curse. You would think that the editor of Doctor Who Magazine would know these things...
• Rather shamefully, Alpha Centauri made a cameo appearance in the now vilified Black & White Minstrel Show.
• When the costume was first revealed to the crew the director, Lennie Mayne - well known for his colourful use of language - couldn't help but point out its similarity to the male sex organ. The cloak was then added, but the director simply thought it now looked like a male sex organ in a cloak...
• Readers of a nervous disposition, or those easily offended, look away now...

The "nude" Alpha Centauri, with a topless Arcturus in the background. Ooh er missus...