Supermassive Black Holes
"Well, a black hole is this really big thing. It's, um, well, basically it's a mass of... hole... out there." -- Jack O'Neill trying to explain black holes to Teal'c in an episode of Stargate SG-1.
Outside of aliens and space travel, black holes may be the most-used idea in science fiction novels, TV shows, and film. They're truly fascinating, spawning ideas of time travel and alternate dimensions.
A supermassive black hole happens to the largest class of black hole. There are two theories about their formation. One involves the collapse of a massive star (100 to 1000 solar masses) that gets bigger by eating its version of fatty foods: surrounding gasses and merging with other structures until it becomes "super-sized."
Another idea involves the collapse of a massive cloud of gas. Instead of exploding like a supernova, it will start to resemble a red giant that sucks in surrounding matter rapidly.
Recently, astronomers using Hubble data have witnessed a supermassive black hole at the center of a galaxy laying waste to a star, sucking it up rather greedily.