M is for... Mire

A parasitic race who provoked conflict with less advanced races, who notorious through the cosmos as powerful warriors. However, they only picked on species which they could comfortably beat - their real aim being to identify and isolate their bravest members. 

These were beamed up to their orbiting spaceship where they were killed for their testosterone and other hormones.

To lure them into fighting, the Mire could conceal their true appearance holographically to look like figures from the target culture. When the Doctor and Clara encountered a Viking party they were taken captive to their village. The Doctor pretended to be Odin - only for 'Odin' to appear in the sky above them.

This was really the Mire commander in disguise. His warriors beamed down to the village, wearing bulky battle-armour which disguised their multi-fanged true form.

After harvesting the best raiders, the Mire were about to depart when a young woman named Ashildr challenged them to a fight to the death with the whole village. The Doctor was forced to improvise a defence.

The Mire armour allowed telepathic communication between warriors, and Ashildr used a captured one to plant false images in the Mire neural network. The Doctor had Clara film them panicking as they thought they were being attacked by a dragon - really only a wooden mock-up.

The Doctor threatened to broadcast the embarrassing footage across the universe, forcing the Mire to withdraw.

Use of the helmet proved fatal for Ashildr, but the Doctor used a Mire battlefield medical device to save her. It caused her to become immortal.

Played by: David Schofield (Odin). Appearances: The Girl Who Died (2015).

• Often called upon to play detectives or criminals, an early film role for Schofield was as the only "Slaughtered Lamb" patron who is prepared to talk to the psychiatrist in An American Werewolf In London. He is best known for playing the villain's henchman in the Pirates of the Caribbean franchise.
• He stepped in late in the day to replace Brian Blessed, who had to withdraw through illness.
• Mire armour at the Doctor Who Festival (2015), and a full costume at the Doctor Who Experience in 2016. The pieces, which were made from lightweight foam, could be handled and worn by the public: