Taken from Michael J. Weldon's Psychotronic Video Guide:
"These are some directors who made the most psychotronic movies (not necessarily the best). All of them have their fans (believe it or not). The list does not include Italians or serial directors.
1. Jesus Franco (Spain)
2. Fred Olen Ray
3. Cirio H. Santiago (Philippines)
4. Al Adamson (murdered in 1995)
5. William Beaudine (last in 1962)
6. Sam Newfield (last in 1958)
7. Terence Fisher (UK; last in 1973)
8. Fred Sears (last in 1958)
9. Jim Wynorski
10. David DeCoteau"