One of the hardiest varieties of the gibbering horrors, these creatures have endured the rigorous vacuum of space long enough to evolve a sort of exoskeletal rind. Once they've made planetfall or boarded a space station they gather up their mass into into crude limb formations to hunt prey with lumbering, clumsy locomotion or futilely reaching out with flacid tendrils. No one is exactly sure why they would do this, since shoggoths are much faster and more effective killing machines in a quasi-liquid state, but the result is definitely unsettling to potential victims. Regardless, they are difficult to exterminate--even with rapid laser fire--due to their incredible powers of recovery.
It's tough to pin down where the "were" begins and ends because too often these nasties are caught between transformation. The lycanthropic virus that causes were-shoggothancy can affect a variety of species (e.g. canine, human, etc.) but determining the original form is often left to DNA confirmation after the beast has been dispatched. Fire seems to work. Lots of it. Yes, use that.
Also called "Deep Dish Shoggoth" are slathering, oozing mounds of cheese, red sauce, and spongy pizza dough. They are just as happy to be eaten as they are to devour prey. Probably why there's not many of them around, save for a few who opted to become crime lords and surround themselves with Italian robo-guards. Come to think of it, that never worked out for them either.
Note: Sh!t Shoggoth was also contemplated, but was deemed too stomach-turning by our astrobiologists. Feel free to list in the comments any shoggoth varieties you've encountered!