O is for... Ohila

Leader of the Sisterhood of Karn (see O is for... Ohica). Ohila succeeded Ohica in this role - the group having taken on board the Doctor's words about the importance of change.

During the Time War, a spaceship crashed onto the surface of Karn. On board was the humanoid pilot, who perished, and the Doctor in his Eighth incarnation. He was fatally injured. He had tried to save the pilot but had been rejected as she saw the Time Lords as no better than the Daleks in the conflict. 

He was offered the Elixir of Life. This had been refined over the centuries so that it now had a range of different properties. These would influence the regeneration and the nature of the new incarnation which emerged from the process.

Having kept his distance from the Time War, the Doctor accepted that it was time to change and participate in the War, and so elected to become a warrior.

Many years later, the Doctor went into hiding when he discovered that an agent of Davros was looking for him. He was ashamed of something he had done in Davros' past, and so took refuge on Karn whilst he prepared himself to confront his old foe - which he did not expect to survive. There he was protected by Ohila and the Sisterhood. The Doctor trusted her enough to give her his Confession Dial, to pass on to his designated 'heir' - Missy.

The Time Lords later imprisoned him within this Dial for millions of years, hoping that he would supply information about a prophesised Hybrid, destined to destroy Gallifrey.

On freeing himself, he overthrew President Rassilon and the High Council who had been responsible for his ordeal. Ohila was present in the Capitol at this time. 

She usually had some influence over him, but on this occasion he rebelled - removing Clara Oswald from the point of time of her death to save her life and shooting the commander of Gallifrey's armed forces before fleeing in a stolen TARDIS.

Played by: Clare Higgins. Appearances: The Night of the Doctor (2013), The Magician's Apprentice, Hell Bent (2015).

• Ohila also features in the prologue to The Magician's Apprentice.
• An early prominent cinema role for Higgins was as Julia in the original Hellraiser movie (1987) and its sequel. Offered a good role in the third, she asked instead to be killed off in the second film of the franchise.
• Her theatre work has seen her wining three Olivier Awards, as well as a Tony nomination for her Broadway debut in 2003.