Someone/Something uses a lots of space (maybe more than really needed), what is this phenomenon called?
Urban Dictionary has this to offer: Space Eater
Any person that takes up more space than normal, either because they are big boned, a close talker, a pack rat, or just spreads out their ish over a wide area.
"...you might want to step a side, it looks like there is a space eater coming this way..."
or
"I hate having conversations with that dude, he is such a space eater."
or
"With such as small apartment, I had no choice but to break it off with that space eater."