Interesting to see this question at this particular time, since Frank McCourt died just about a week ago.  Angela of the title was McCourt's long-suffering mother, forced to raise her family in poverty in Ireland while her husband bounced around from place to place, largely unable to hold a job and drinking away his paycheck when he actually received one.  The main characters, then, are Angela, McCourt's father Malachy, twins Oliver and Eugene, a sister, Margaret, and two more brothers, Michael and Alphie.  McCourt was born in Brooklyn, as were Margaret and the twins.  The family moved back Ireland shortly after Margaret's death; the twins died about a year later, after which Michael and Alphie were born.