Who had the seven Horcruxes?

Answer 1

No one was specifically looking after them, but here goes (sorry if its incorrect):

1. The Diary - this belonged to Tom Riddle (Voldemort).
2. The Ring - it belonged to Marvolo Gaunt (Riddle's grandfather), and this eventually landed in Albus Dumblredore's hands, who destroyed it.
3. The Locket - belonged to Salazer Slytherin, and was passed down into the Black family (heirloom) to Regulus Arcturus Black - a death eater - who gave it to Riddle to 'use' (not knowing at the time it would be used as a Horcrux). Eventually, he figured out Riddle's secret and wanted to destroy it, hoping Riddle to become mortal once more. The locket was hidden in the cave, and he got the locket and duplicated it, so there were two lockets, the real and the fake. Inferi got to Regulus before he could escape, and they killed him, so Kreacher (the Black's house elf) swapped the real locket with the fake one, took the real one and attempted to destroy it (you should know the rest of it by now).
4. The Cup - belonged to Helga Hufflepuff.
5. The Diadem - belonged to Rowena Raveclaw, then stolen by her daughter, Helena.
6. The Snake - Nagini, who belonged to Voldemort, and become a Horcrux when he killed Bertha Jonkins in Albania.
7. Harry Potter - was made a Horcrux by accident, and Voldemort doesn't know this.