R is for... Ranquin

Leader of a tribe of Delta Magnans, who had been forcibly relocated from their planet onto its third moon - displaced by colonists from Earth. His people were green-skinned humanoids, whom the colonisers nicknamed "Swampies" due to their natural, marshy habitat. It was the similarity in environment which led to them being placed into a reservation on the third moon.

Ranquin acted as high priest to their god Kroll, who had the form of a gigantic squid-like creature. Legend had it that Kroll had once swallowed a previous high priest, along with their sacred totem.

The entity was now said to sleep beneath the waters of the moon's lagoon.

When the colonists began taking an interest in the rich methane supplies of the satellite, building a refinery offshore close to his village, Ranquin entered into a partnership with a gun-runner named Rhom-Dutt, to supply weapons with which to attack the installation. He was unaware that the gun-runner was really in the employ of refinery manager Thawn, who sought an excuse to wipe out the "Swampies" whom he hated. The weapons would be defective, but still provide the provocation he wanted.

Part of Ranquin's sacred duties were human sacrifices to Kroll. Behind a wall, hidden from view, the victim would be killed by a tribesman dressed as the creature. This fate almost befell Romana, who had come here with the Doctor in search of the fifth segment of the Key to Time.

Kroll proved to be a real creature - wakened from hibernation by the activities of the refinery. The Doctor deduced that it was the cause of the rich methane supply.

Threatened with sacrifice, the Doctor discovered that Ranquin wasn't susceptible to hypnotism.

He eventually led his warriors on an attack on the refinery, and Thawn was killed. Kroll attacked the rig and Ranquin attempted to appease it - only to fall victim to it.

Played by John Abineri. Appearances: The Power of Kroll (1978/9)

• This was Abineri's fourth and final appearance in the programme. He first played Dutch engineer Van Lutyens in Fury From The Deep, before taking on the more substantial role of General Carrington in The Ambassadors of Death. His third appearance was as Railton of the Marine Space Corps in Death to the Daleks. 
• He played Herne the Hunter in Robin of Sherwood, and took on the role of Blake's uncle in the Blake's 7 episode "Hostage" after the death of Duncan Lamont (his co-star in the Dalek story).
• Late in his career, he became well known for playing the butler in a popular Ferrero Rocher advert - ironically set at an ambassador's ball.