Possession

Possession was the act of one being taking over the body and mind of another.

Examples of possession
Fenric possessed Doctor Judson and Captain Sorin, allowing him a direct hand in his revenge against the Seventh Doctor. (TV: The Curse of Fenric)

The Beast possessed Toby Zed, giving him the ability to breathe fire and survive in areas without oxygen. (TV: The Impossible Planet / The Satan Pit)

The Torajii sun possessed Hal Korwin, Dev Ashton and the Tenth Doctor, giving them the ability to vaporise a being by looking at them. (TV: 42)

The Isolus possessed Chloe Webber, giving her the ability to make drawings come to life and living things become drawings. (TV: Fear Her)

Cassandra O'Brien possessed Rose Tyler by means of an illegal psychograft, when she decided she needed a new human body. She later possessed the Tenth Doctor and her servant, Chip. (TV: New Earth)

The Bane possessed humans who consumed Bubble Shock!, turning them into zombies at their command. (TV: Invasion of the Bane)

The Master possessed bodies of others to avoid death. Two such people he possessed were Tremas of Traken (TV: The Keeper of Traken) and Bruce. (TV: Doctor Who)

The Family of Blood possessed four humans, giving the Family non-gaseous bodies to travel around in. (TV: Human Nature / The Family of Blood)

The Gelth possessed dead humans, giving the Gelth bodies to use as "vehicles". (TV: The Unquiet Dead)

The reservoir of evil was capable of possessing sensitives in geographical locations metaphysically close to them. Daniel O'Kane was possessed in 1945 and killed his mother, father and two sisters. In 1994, he was returned to Hawthorne and killed ten people, including William Bruffin and Colin Dove. Peter Russell was later possessed, as was Patient One. (HOMEVID: The Zero Imperative)

The Midnight entity possessed Sky Silvestry, giving her the ability to steal the voices of others. (TV: Midnight)

Death possessed Owen Harper after he was reanimated. (TV: Dead Man Walking)

Clara Oswald was possessed by Kali. (COMIC: The Swords of Kali)

The Psionovore Marchosias possessed Senator Waldo Pickering, giving him superhuman strength and allowing him to directly feed on others' fears. (AUDIO: Minuet in Hell)

The Pandora entity possessed Inquisitor Darkel's mind, killing her. She had previously occupied other host bodies, but she had always been driven out. (AUDIO: Gallifrey)

Krem-ling and others like him possessed the bodies of the individuals they psychically fed on. (PROSE: The Vampires of Crellium)

The Ravenous were able to learn "new tricks" during their isolation in the prison dimension, including possession. (AUDIO: Deeptime Frontier)