Vocalization of monster

Metal pressed against dry ice.
– Paul Arnold

Slide a straw up or down in a McDonald’s large drink plastic lid. Trying pitching it down, stretching it. And voilá! McZilla.
– Max Hodges

Certain kinds of canned dog food make useful sounds as the food comes out of the can. The chunky stuff isn’t so good, but the tightly packed all-one-mass kind makes gushy sucking sounds when the air on the outside of the can is sucked into the can to replace the exiting glob of dog food. This sound can be used as an element in certain kinds of monster vocalizations.
– Ashley Walker

If you need some sounds to work from, these sfx libraries can be a good starting point.