Limpy (The Girl Who Died)

"Limpy" was a Viking who was trained to be a warrior, and given a nickname by the Twelfth Doctor, when facing an imminent attack from the Mire. The Doctor chose the name "Limpy" after he injured his leg whilst training with a sword.

It is heavily implyed that his nickname his He is the villager responsible for blowing the horn as the raiding party returned from their trip.

Biography
When a raiding party returned to their village with the Doctor and Clara Oswald as prisoners, "Limpy" was the villager who blew the horn to announce their arrival. Shortly afterwards the Mire, whose leader was posing as Odin, also arrived, and abducted several of the village's warriors, as well Ashildr and Clara. When Ashildr declared war on the Mire, "Limpy" was one of the villagers chosen to train with the Doctor to become a true Viking warrior.

The Mire returned the following day, where "Limpy" and the other remaining villagers were partying according to the Doctor's plan, which used a combination of electric eels, and Ashildr using a Mire helmet to project the image of an attacking dragon. (TV: The Girl Who Died)