Eye

The eye was a body part used for vision.

Some Silurians had a third eye, which could be used for telepathic purposes or as a weapon. (TV: Doctor Who and the Silurians, PROSE: Blood Heat, AUDIO: Bloodtide)

Pigmentation dispersal could cause the eye to change colour. Leela's eye colour changed from brown to blue after the explosion of a Rutan mothership prompted pigmentation dispersal and left her temporarily blind. (TV: Horror of Fang Rock)

used Chang Lee's human eyes to open the Eye of Harmony in the Doctor's TARDIS (TV: Doctor Who)

After failing to rescue Omega from the black hole he was trapped in, Savar was forced to leave his damaged TARDIS in an escape pod. The I intercepted the pod, taking all relevant technology. However as Time Lord technology utilised retinal verification, they also extracted his eyes. (PROSE: The Infinity Doctors, PROSE: The Infinity Doctors, Seeing I)

An Ood's eye colour changed with the level of telepathic activity, normally glowing bright-red but turning to white when not connected to a hive mind. Humans, who only knew the Ood in their telepathy-disabled form, misinterpreted the presence of red eyes as a disease, known as "red-eye". (TV: Planet of the Ood) Under the control of House, one Ood's eyes glowed green. (TV: The Doctor's Wife)

A Dogon's sixth eye allowed someone to look back clearly on their life and make better choices, especially if swallowed. (TV: Random Shoes)