So I was looking under the Harry Potter tags, and I think these are duplicates, but I'm not sure if mods are considering Tom Riddle and Voldemort to be separate entities. But I've listed them anyway.

Albus Dumbledore/Tom Riddle (Harry Potter)
Albus Dumbledore/Tom Riddle | Voldemort (Harry Potter)

Harry Potter/Tom Riddle (Harry Potter)
Harry Potter/Tom Riddle | Voldemort (Harry Potter)
Harry Potter/Voldemort (Harry Potter)

Remus Lupin/Sirius Black (Harry Potter)
Remus Lupin/Sirus Black (Harry Potter) (spelling error on Sirius in this one)

Jane Marple/Minerva McGonagall - I don't think there's a Jane Marple in HP, just in Agatha Christie, and if so should be in Crossovers.