25 October 1975: broadcast of first episode of The Pyramids of Mars. The Doctor and Sarah land in the future UNIT headquarters, the Scarman brothers' family home, and encounter robotic mummies and various Egyptian relics.
25 October 1980: broadcast of first episode of Full Circle; first appearance of Adric. The Tardis falls into E-Space; Mistfall threatens the people of Alzareus; and the Marshmen rise.
25 October 1986: broadcast of fourth episode of Mindwarp (ToaTL #8). Peri is killed by brain transplant!!! (Or is she?) Her last appearance as a regular character anyway.
25 October 1989: broadcast of first episode of The Curse of Fenric. The Doctor and Ace, and also a Soviet military mission, land at Maiden's Point during the second world war, and find themselves decoding ancient messages.
25 October 2010: broadcast of first episode of Death of the Doctor (SJA). The Doctor is reportedly dead; and Jo Jones, formerly Jo Grant, comes to pay her respects.
25 October 2014: broadcast of In the Forest of the Night. Trees have taken over the Earth.