Sir Lewis de Bourgh is a character mentioned in Pride and Prejudice. He never appears in the book, having died before the course of the novel, but is mentioned several times.
Sir Lewis was married to Lady Catherine, a daughter of an earl. They had one child, Anne de Bourgh, who is the sole heir of the de Bourgh properties, namely Rosings Park. This is because there was no entail, and if there was, the de Bourgh family had enough money in order to smash it.
Lady Catherine mentioned that although Sir Lewis was not aristocratic, he was a gentleman and his family has a long and good history in London society. This is the same for George Darcy, Mr. Darcy's father.