Glenn Manning

First appearance: The Amazing Colossal Man (1957)
This appearance: War of the Colossal Beast (1958)

In the Amazing Colossal Man, Lt. Col. Glenn Manning was hit with radiation. Instead of contracting cancer and dying he grew to fifty feet tall, went insane and goes on a rampage. The military eventually knocked him off the Boulder Dam, killing him. Or so they believe. Upon receiving reports of strange food truck robberies in Mexico, his sister (who according to the first movie didn't exist), an army guy and a scientist decide that Glenn is alive and committing these crimes. Turns out they are right Glenn didn't die in fact plutonium radiation made him ten feet taller, melted off half his face, stupider and addicted to loaves of bread. Our group of intrepid heroes capture Glenn, drug him and bring him back to the States in order to cure him, or something.
Back home Glenn wakes up and goes on a rampage in Los Angeles. What can stop and Amazing Colossal Man?
Coincidentally (or not) the man who made this movie Burt I. Gordon's initials spell BIG.