Speaking of the Animorphs, they seem to have counterparts in the least likely of places- the gang from That '70s Show, they map pretty well to each other (Eric = Jake, Hyde = Tobias, Kelso = Marco, Jackie = Rachel, Cassie = Donna, and Ax = Fez).
Almost every single adaptation of the books Alice's Adventures in Wonderland and Through the Looking-Glass so far have made the Red Queen and the Queen of Hearts (two different characters from completely separate books) into an overtly threatening antagonist (which neither of the Queens were).
Considering Nancy Drew was created at all simply because publisher Edward Stratemeyer noticed how many girls were reading The Hardy Boys and realized there was an untapped market, it's not impossible to draw lines between the series. There's the intelligent, bookish one (Nancy/Frank), the extremely athletic one with slight temper issues (George/Joe), the slightly overweight character whose always the most reluctant and afraid (Bess/Chet.) Both had fathers in the legal field (Carson Drew was a lawyer/Fenton Hardy was a cop turned detective,) a very vague maternal figure (Kate Drew is dead/Laura Hardy is alive but was little more than scenery), and a secondary maternal figure (Hannah Gruen/Aunt Gertrude.)
And Harry himself can be compared to Luke Skywalker. Both are orphans who have some sort of connection to the Big Bad (Luke is Darth Vader's son, Harry has some of Voldemort's powers due to Voldemort's curse failing to kill him) who were raised ignorant of their true nature by their aunt and uncle in order to keep them safe, before being trained by a wise old mentor in the ways of magic/the Force.
A white-bearded elderly wizard considered to be one of the best of his time, mentored the Big Bad when the latter when younger, watched over the main protagonist when he was younger after leaving him with fantasy forbidding relatives, fought and defeated a dark lord when he was younger, and died at the hands of The Dragon. This description works for both Obi-Wan Kenobi and Albus Dumbledore.
Ramsay Snow from is basically an exaggerated and slightly older version of Joffrey Baratheon from the same series, minus the cowardice. Both are bastards in both senses , seek approval from a distant father figure, are basically incapable of long-term thinking and completely sickandtwisted. Ramsay is basically what Joffrey would be if he grew up unsupervised in the middle of nowhere, instead of in the Red Keep with the eyes of the world on him.
Robb Stark and Liu Bei: Both are leaders of the designated "good guy" factions who rebel against the more powerful "evil" factions, have the best warriors (even having a Boisterous Bruiser, Greatjon Umber and Zhang Fei as some of their respective greatest warriors), are prone to bouts of Honor Before Reason to a fault, and ultimately lose the war and die.
Alternatively, Daenerys Targaryen can be compared with Liu Bei, as both are relatives of the previous, fallen dynasty (Targaryens and Han respectively), and both are noted for their kindness towards peasants (and slaves in the previous case).
Tywin Lannister and Cao Cao: Both are debatably evil, yet ambitious ruthless warlords who want to restore order to the realm while fighting to put their families on the top, and eventually gain de facto control over the realm by becoming a regent. Both are also related to the nominal ruler by marriage of their daughters.
House Tyrell and the kingdom of Eastern Wu: Both serve as the biggest rivals to the faction containing the emperor (Lannisters and Cao Wei), but they generally act by forming opportune alliances. Both factions also place a high value on family.
Petyr "Littlefinger" Baelish and Sima Yi: Tricky figures who start out as minor figures but eventually bring about the downfall of the more powerful "evil" faction and come out on top.
Gregor Clegane and Lu Bu: Both are practically unbeatable warriors with violent tempers and no morals or sense of honor whatsoever.
Peter from Divergent is a knife-wielding, green-eyed, dark-haired enemy of our protagonist with a violent, murderous streak, which is similar to Cato from The Hunger Games.