A polythropic (shape shifter) mythical creature that has the ability to assume the shape, and or personality, and or soul, of the humans or animals it kills and consumes.
The monster from John Carpenter's The Thing was the best amalgamorph ever to appear in movies, even though the one in Dean Koonz "Phantoms" was scarier!
Being of different backgrounds, ethnicity, groups, or company departments coming together. Two or three or four or more in one. Lots of personalities intertwined, perhaps in your own warped mind. An amalgamation of people or personalities.