Adaptational Context Change: As Colonel Munro from The Last of the Mohicans really existed, it was a Foregone Conclusion that he should die of heart failure before 1757, the year the novel is set in, is out. However, in the novel his death is attributed not to the exhaustions of the campaign, but to his grief over the death of his (fictional) daughter Cora.
Fair for Its Day: Cooper in his day was seen as a friend to Native Americans and commended as such e. g. in a eulogy by the Chippewa chief George Copway (Kah-Ge-Ga-Ga-Bow). Partly to get to know them better, he would attach himself to delegations from Western Plains tribes to Washington. Today, The Last of the Mohicans is somewhat controversial for popularizing the concept of "noble savages" who were loyal to the English and Americans versus "ignoble savages" who weren't. On the other hand, Magua (who is struggling to regain the dignity he lost because the white men taught him to drink) is one of Cooper's complex and interesting characters, and the book did popularize the romantic notion of Indians as culturally superior and better adapted to the natural environment. The 1992 film skirts this by showing Indians on an equal footing with whites at a time when they were just fighting to keep their land. That and hiring Russell Means to play Chingachgook (he was well-known for activism on behalf of Native Americans) made the film much more well-received in the Native community.
Germans Love David Hasselhoff: Cooper was the first American author to achieve not just recognition, but also bestselling commercial success in Europe. He was lionized while he lived in France - The Prairie was written in Paris - and influenced not just a number of French, German and British writers who would write (proto-)Westerns modeled on the Leatherstocking Tales, but also for instance Balzac's novel Les Chouans and Alexandre Dumas père's Les Mohicans de Paris. And Cooper occupies a to American eyes astonishing amount of room in the Soviet and later Russian English Literature syllabus. In Germany he was hugely influential as well and is second only to Karl May in terms of literature dealing with Native Americans, to the point that many of the tropes, cliches and misconceptions of Cooper's work are "common knowledge" about Native Americans to this day in Germany.
Seinfeld Is Unfunny: Although Cooper's writings may not be to the tastes of many modern readers, they were very progressive for the time, pioneered an all in all very positive portrayal of Native Americans and earned Cooper a lot of hate e. g. from politicians who then set in motion the displacement of Indians from their ancestral homes. The problem for him is that his literary style, romanticism, fell out of fashion and that for many people today Cooper's noble savages aren't noble enough.
What Could Have Been: Cooper for a time planned to write a Leatherstocking novel set during the American Revolution, which would have made it six in all. The Massachusetts-based novel Lionel Lincoln was the first of the intended series Legends of the Thirteen Republics, which would have reflected the role of each of the original colonies in the American Revolution. Lionel Lincoln's poor critical and commercial reception prevented the other twelve from ever being written.
Write What You Know: Most of Cooper's novels are set in America, on sea, or both. The Spy is set in Westchester County, where he lived for a time. With the exception of The Prairie, the Leatherstocking Tales are set in places where he had actually been, notably Lake Otsego and other parts of New York. Templeton in The Pioneers is a satirically sharpened expy for Cooperstown (where Cooper grew up and later settled down), and its founder Marmaduke Temple is partly based on the author's father. In The Deerslayer Cooper is effectively describing his backyard, which makes Mark Twain's uninformed critique of the Cooper's descriptions (Twain apparently never even visited the place) unintentionally funny.