Spider-Man Fan Film (Donald F. Glut, 1969)
Blackstar - Episode 1: "City of the Ancient Ones"
Blackstar must save the hypnotized sorceress from Overlord, and rescue the shapeshifter elf and gnome/dwarves from her magical ring!
Galaxy Trio - Ep9 "Computron Lives", Ep7 "Titan, the Titanium Man" & Ep12 "Demon Raiders" (Hanna/Barbera, 1967)
Computron's ray gun turns people into robots, and...(spoiler alert) robots into people! Also, Titan, the Titanium Man and Demon Raiders!
Thor and The Avengers: Molto and the Lava Men (1966)
Lava men are inhuman monsters that threaten all of humanity! Perhaps the Hulk can be persuaded to help the Avengers by a... friend? Great style!