I think I have to agree that the saddest episode of Doctor Who for me is The Girl in the Fireplace. It's one of the few times Moffat doesn't undercut his own tragic moment with a last-minute twist ("Well that's alright then!" or otherwise) and the episode is so much better for it. Yes, her death is part of the historical record but he could have pulled sci-fi shenanigans there and didn't.
Other moments that move me to sad tears:
Other moments that move me to sad tears:
- Adric's death is pretty heartwrenching.
- The Doctor erasing (well, locking away) Donna's memories of him (even with the reboot series' events).
- Wilf sobbing as the Doctor departs for his regeneration.
- The Doctor's farewell to Susan.