46 Pre-2001 Essential Genre Films That Every Geek Should See

By “pre-2001,” I mean films that were released before 2001: A Space Odyssey (1968)

I selected these films using Phil Hardy’s Encyclopedia of Science Fiction Movies (1984), as well as my classroom experience in college.  As with most lists of this nature, the choices are mostly subjective, but they do seem to be backed up by critical comments throughout film history, and especially SF film history.

My criteria were simple:
-> The film had to be released prior to 2001;
-> The film could not be a serial;
-> The film must not be a sequel;
-> The film must be generally available for viewing

A Trip to the Moon	1902
Die Spinnen (The Spiders)	1919
Der Golem	1920
The Cabinet of Dr. Caligari	1920
Dr. Mabuse der Spieler (Dr. Mabuse: The Gambler)	1922
Nosferatu	1922
Phantom of the Opera	1925
Metropolis	1927
Spione (The Spies)	1928
Frankenstein	1931
Dracula	1931
Island of Lost Souls	1932
The Mummy	1932
White Zombie	1932
King Kong	1933
Things to Come	1936
Dr. Cyclops	1940
The Wolfman	1941
Destination Moon	1950
The Thing (from Another World)	1951
The Day the Earth Stood Still	1951
War of the Worlds	1953
The Beast from 20,000 Fathoms	1953
20,000 Leagues Under the Sea	1954
Them!	1954
Gojira (aka, Godzilla, King of the Monsters)	1954
Creature from the Black Lagoon	1954
This Island Earth	1955
Invasion of the Body Snatchers	1956
Forbidden Planet	1956
Plan 9 from Outer Space	1956
20 Million Miles to Earth	1957
The Incredible Shrinking Man	1957
The Fly	1958
The Blob	1958
The Time Machine	1960
The Mysterious Island	1961
The Absent-Minded Professor	1961
X: The Man with the X-Ray Eyes	1963
The Nutty Professor	1963
The Day of the Triffids	1963
Dr. Strangelove	1964
The Fantastic Voyage	1966
Fahrenheit 451	1966
Batman	1966
Planet of the Apes	1968*

*Planet of the Apes beat out 2001 by 3 days
The entries in bold are the ones I have seen. The others are ones I plan to. 
Feel free to add your own choices in the comments section!