Child (Have You Seen This Man?)

In 1987, the Ninth Doctor saved a child from being hit by a VW Beetle. Before disappearing into the crowd, the Doctor told David Gee and his wife that "[he'd] regret that in the morning". (PROSE: Have You Seen This Man?)

Behind the scenes
The seeming inference is that this child would later adversely affect human history, so the Doctor saving the child was a moment of compassion that may have larger consequences in the relative future. However, this character does not appear to be a specific reference to any fictional or real character, more of just an archetype within time travel ethics.