1. The Dollars Trilogy (Sergio Leone, 1964-66)
A Fistful of Dollars, For A Few Dollars More, The Good, the Bad, and the Ugly

2. The Apu Trilogy (Satyajit Ray, 1955-59)
Pather Panchali, The Unvanquished, The World of Apu

3. The Original Star Wars Trilogy (George Lucas, 1977; Irvin Kirshner, 1980; Richard Marquand, 1983)
Star Wars, The Empire Strikes Back, The Return of the Jedi

4. The Bill Douglas Trilogy (Bill Douglas, 1972-78)
My Childhood, My Ain Folk, My Way Home

5. The Before Trilogy (Richard Linklater, 1995-2013)
Before Sunrise, Before Sunset, Before Midnight

6. The Godfather Trilogy (Francis Ford Coppola, 1972-90)
The Godfather, Part II, Part III

7. The Three Colours Trilogy (Krzysztof Kieslowski, 1993-94)
Blue, White, Red

8. The Andrzej Wajda War Trilogy (Andrzej Wajda, 1955-58)
A Generation, Kanal, Ashes and Diamonds

9. The Dead Trilogy (George A Romero, 1968-1985)
Night of the Living Dead, Dawn of the Dead, Day of the Dead

10. Back to the Future Trilogy (Robert Zemeckis, 1985-1990)
Back to the Future, Part II, Part III

If you like your top ten trilogies peppered with Lord of the Rings, Batman, Spider-Man, Iron man, Jason Bourne, Toy Story and The Matrix et al, you are probably twelve years old and should look elsewhere.

Previously on Barnflakes
Top 10 movie sequels better than originals