24. The Tenth Doctor Meets River Song
From: "Silence in the Library"/ "Forest of the Dead"
Premiere: May 31, 2008 / June 7, 2008
A two-parter from David Tennant's third season as the Tenth Doctor, this pensive, creepy mystery introduces two of the best creations in the revived series. One is the Vashta Nerada, a species of swarming micro-organisms that emerge from shadows to strip their victims to the bone, leaving a corpse repeating its last words over and over. The other is Professor River Song (Alex Kingston), a red-haired tornado of a mercenary archaeologist. The Doctor meets River for the first time here, and her story ends in "Forest of the Dead" – yet through the paradox of mutual time travel, the two have a lively future ahead, including a major familial twist.