Scrooge McDuck is some greedy idiot who loves money more than his own mother. He is the richest duck alive (and possibly stupidest, but Donald Duck provides tough competition in that category). He likes to break into good people's houses and steal their stuff (sorta like an anti-Santa Claus). He has three stupid minions grandchildren that are some more of the stupidest ducks alive.
Scrooge's main goal in life is to have as much money as possible. This is why he doesn't pay taxes, and he kills police whenever they try to kick him out. Nobody knows where the last name "McDuck" came from, because his parents' last name is Clom.