This ugly cuss is called Mutagen Man.
He's a Teenage Mutant Ninja Turtles villain character and was originally released in 1990.
The gimmick for this guy is that his innards are free floating inside his "glass" body. You can even fill him up with water (which I did) in order to enhance the effect. I considered filling him with slime, but the slime I have is not transparent enough and would make seeing his innards impossible. I also considered adding some food coloring to the water but decided, for now, to stick with regular old clear cool delicious H2O.
There's a lot of detail on his insides and his outsides too. He even has some little plastic bits floating inside (like a wrench and a little turtle!)
He's like a monstrous snow globe!
I got this TMNT character second-hand recently, so I don't know anything more about him. I do know he's missing an accessory or two (there's a space on his back for what looks like a scuba-tank apparatus) so if anyone has spare Mutagen Man accessories laying around, I'll take 'em!