This is a vintage Japanese Godzilla from Bullmark, molded in die-cast metal with a variety of unique features (particularly for Godzilla!). I am not the original owner, and lucked into this incomplete (albeit attractive) rarity for a very reasonable price some years ago. A few different color variations were produced in the handful of years that these were available; I believe a brownish version preceded this green version by a few years.
Godzilla's jaw open as you turn his head to the left or right — a bump under his chin causes it to close when turned face-forward.
Here's where it gets interesting. His chest opens out, revealing an interior where a small plane once resided, as well as several missiles that could be fired from two spring-loaded slots by pressing the red levers on his back.
There is also a telescoping feature that represents... well... I don't exactly know what that's supposed to represent. I guess we'll just have to assume that Godzilla is happy to see you.
While I wouldn't mind having a complete, boxed example, these can get very pricey. (A decapitated one is currently on eBay for more than $100!)
There are several other Godzilla characters in this Bullmark series — I'd particularly like to pick up the die-cast Gigan that my friend Mark had growing up. But those tend to run even higher than Godzilla!
Check back next week when I'll feature yet another item from my Godzilla collection.