Lobster Man, though? He showed up in a scene and we ran like hell. We learned REAL fast in the first couple encounters with him that he was nigh unstoppable and absolutely Tonberry horrifying. God that character was scary. He was finally destroyed by divine intervention in the last session...
And we never did learn who or what he was. He was just a faceless, implacable, EXTREMELY deadly horror that was dedicated to our destruction.
One time, we were investigating the studio of an allegedly corrupted sculptor who's art was getting weirder and weirder. We were in the studio with all these creepy statues, some of them covered in tarps. One of the PCs pulled the tarp off a statue and Marc, the GM, said, "Oh, it's Lobster Man!"...
The PC who unveiled it said, "You mean, like, a statue of Lobster Man?" To which Marc replied, "Noooooo, it's Lobster Man. Roll initiative" The amount of hooting and hollering and scampering that followed has been the stuff of legend in that gaming group for almost 20 years now.
Also, LOL, I should describe him. He was this weird amalgam of humanoid and crustacean that stood about 8 feet high and was covered in thick, chitinous armor. He had lobster/crab claws for hands, and could snap clear through an AK-74 like it was butter and punch holes through armored vehicles.