4. Lucie Miller/To the Death
So the Eighth Doctor returned to mid-22nd century Earth a few stories back and was reunited with his daughter, Susan, who had a son named Alex; the Doctors half-Time Lord great-grandson. The Doctor also eventually acquired a new companion named Lucie Miller and later another named Tamsin Drew. Over the course of this two-part story, Lucie was sickened, maimed and crippled, Tamsin was betrayed by a renegade Time Lord, the Monk, and both of them, plus Alex, were killed by the Daleks. So its a wacky, light-hearted, upbeat kind of story. This is one of the only times Ive ever found the Daleks to be truly threatening. Here they represent pure, total evil, and do a great job of it. The end is easily one of the most shocking moments in the entire cannon of Doctor Who, leaving the Doctor shattered, and moving him ever closer to being the person who could fight the Time War.