Frank Ellis

 was a scientist and the father of Karen Ellis.

At one point, Frank worked with Ian Chesterton to repair a camera on the Hubble space telescope. As they worked on the camera, an entity in the Monoceros constellation travelled along the infrared rays and took over Frank.

Years later, as Frank lay dying in hospital, Frank's daughter brought Barbara Chesterton to see him. He was frail and wasting away, and kept saying words like "unicorn" and "alone". The next day he died. A cyst was removed from him; Ian later discovered that the cyst had contained nerve cells from the entity. (PROSE: Distance)