Ten Doctor Who episodes:

1. The Time Monster (1972)
2. Survival (1989)
3. The Invasion (1968)
4. The Stones of Blood (1978)
5. Terror of the Zygons (1975)
6. The Dalek Masterplan (1965)
7. Snakedance (1983)
8. The Ultimate Foe (1986)
9. Frontier in Space (1973)
10. Aliens of London (2005)

Happy Doctor Who Day! The first episode of Doctor Who aired on this date in 1963.

By the way, it should be noted that "The Ultimate Foe" is an unofficial title; officially, it's known as episodes 13-14 of "Trial of a Time Lord."