Mrs. Finnigan was a witch and the mother of Seamus Finnigan (PS7).
Harry Potter met Mr. and Mrs. Finnigan at the 1994 Quidditch World Cup (GF7).
When Dumbledore died, Mrs. Finnigan went to Hogwarts to take Seamus home. Seamus, however, refused to leave before Dumbledore's funeral. They had a shouting match about it in the entrance hall. Seamus eventually won out. Mrs. Finnigan decided to stay is Hogsmeade and attend the funeral, too, although she had a difficult time finding a place to stay since so many other people had come to town ahead of the funeral (HBP30).
Mrs. Finnigan is married to Mr. Finnigan, a Muggle. Their son, Seamus, is a half-blood wizard (PS7).