SPEAKER/Episodes

Season Two

 * Ep 13 - Welcome Back

Season Three

 * Ep 37 - Here There Be Monsters
 * Ep 43 - This Fear

Season Four

 * Ep 48 - Your Myriad Curses (mentioned only)
 * Ep 49 - The Harshness Of Truth
 * Ep 53 - Left Undone
 * Ep 58 - Best Interests

Season Five

 * Ep 62 - The Games You Play (mentioned only)
 * Ep 70 - The Birth of Silence (Earth version)

Season Six

 * Ep 76 - Trust
 * Ep 78 - The Eyes That Watch You
 * Ep 79 - Simple Truths
 * Ep 80 - By Your Actions
 * Ep 81 - This Cave

Chronological Order

 * Ep 62 - The Games You Play (mentioned only)
 * Ep 70 - The Birth of Silence (Earth version)
 * Ep 13 - Welcome Back
 * Ep 37 - Here There Be Monsters
 * Ep 43 - This Fear
 * Ep 49 - The Harshness Of Truth (second version from this point forward)
 * Ep 53 - Left Undone
 * Ep 58 - Best Interests
 * Ep 76 - Trust
 * Ep 78 - The Eyes That Watch You
 * Ep 79 - Simple Truths
 * Ep 80 - By Your Actions
 * Ep 81 - This Cave