7. “Planet of the Spiders”
Up to this point, Jon Pertwee was the longest serving Doctor by a couple years. He was the first Doctor of the color era, and brought the action-y aspect we all know and love to the show. What better way to send off Jon Pertwee than by putting him up against... giant spiders? What the what? Although not as clunky as "The End of Time" or as ridiculous as "Logopolis", "Planet of the Spiders" is a just okay conclusion to the Third Doctor's story. At least his actual regeneration scene is pretty memorable.