Doctor Who: Ranking the top 10 David Tennant episodes

5. “School Reunion” Season 2, Episode 3

Not only is “School Reunion” a great David Tennant episode, but it marked the return of the two of the original series’ most beloved companions, Sarah Jane and K-9. By bringing these two back, “School Reunion” officially connected the original series to the reboot and laid the groundwork for the spinoff series, The Sarah Jane Adventures.

The beauty and tragedy of this episode are executed beautifully by both David Tennant and Billie Piper, and it’s one I often go back and rewatch from time to time. Rose is perturbed by the idea that she isn’t the only companion who has been in the Doctor’s life. In fact, there have been many others, which doesn’t exactly make her feel beloved or special.

There’s a moment when Tennant’s Tenth Doctor tells Rose:

"I don’t age. I regenerate. But humans decay, you wither and you die. You can spend the rest of your life with me. But I can’t spend the rest of mine with you. I have to live on, alone. That’s the curse of the Time Lords."

It’s a jarring reminder that even though the Doctor isn’t human, he still feels pain and love and loss. He has to deal with the fact that companions come and go, so at the end of the day, while Rose’s feelings matter tremendously, it is the Doctor who has to deal with the most loss, over and over again.

I love the way Tennant plays the Doctor’s internal devastation, and yet can still flip back to the happy-go-lucky Time Lord we know when there’s reason to celebrate again. It’s one of Tennant’s strongest performances. Couple that with the return of Sarah Jane and you have one heck of an episode.