I'll start with one of Galt's best: The Provost (1822), the memoir of a small town tailor who inherits a bit, marries well, and sets his sights on politics. Over fifty years, he is elected Provost of the town three times. "Elected" means - well, this is the 18th century.
Since the book is Mr. Pawkie's own story of his public life, the short chapters often have titles like "Of the Public Lamps" and "The Improvement of the Streets." Pawkie's private life is only barely in the book. It's about his political career, what he did for the town, his setbacks and successes. Incidentally, it traces the social changes in the town.
So far, so dull. Except that Pawkie turns out to be a genuine Machiavellian. He does not admit to having read The Prince (Galt sure did), but it turns out he has completely intuited and assimilated that book's principles. Pawkie never seeks office - he is always asked to serve. Enemies are never directly opposed, but somehow always undermine themselves.
See Chapter 39, "The Newspaper," where Pawkie destoys the poltical effectiveness of the town's first newspaper ("a rank exuberance of liberty") not by trying to suppress it but by advertising in it, "which I did by the way of a canny seduction of policy," eventually turning it into a "very respectable instrument of governmental influence and efficacy."
Pawkie is also just a wee bit corrupt. He protests that he is honest, but cannot help revealing the personal advantage he accrues from one scheme or another. It's the subtlest touch of the novel - he can't help telling us about his corruption, just as he tells us about how he manipulates everyone in town, because of his pride in his own cleverness.
As time passes, he insists that he only behaved as people did back then, and that he has changed with the times, yet in the last chapter we find him manipulating the town council into giving him "a very handsome silver cup" for his retirement. The last sentence:
Posterity, therefore, or I am far mistaken, will not be angered at my plain dealing with regard to the small motives of private advantage of which I have made mention, since it has been my endeavour to show and to acknowledge, that there is a reforming spirit abroad among men, and that really the world is gradually growing better--slowly I allow; but still it is growing better, and the main profit of the improvement will be reaped by those who are ordained to come after us.
In The Provost, Galt creates a technically perfect unreliable narrator. Pawkie is not concealing, or revealing, anything too dramatic. He doesn't, I don't know, kill anybody, or rob the orphan's fund. He's quite benevolent, in a way. He just shaves off his little percentage.