Doctor Who: Every Doctor's Darkest Moment

15. The First Doctor - Attempted Murder Of A Caveman

The First Doctor never saw himself as a hero, and some of his darker actions prove this. Many of them come in An Unearthly Child, from the kidnap of Ian and Barbara to an attempted murder.

When the caveman Za is wounded by a wild animal, he becomes an impediment to the TARDIS crew's escape. So the Doctor picks up a rock and advances on him, seemingly to put him out of his misery.

In these very early days of the First Doctor, he clearly puts the survival of himself and Susan above all else. It was an incredibly dark moment that established the Doctor's more alien, logic-driven morality.