Who gave Tom Riddle his first exposure to Horcruxes?

Horace Slughorn

Which single was the first surprise release from Swift’s album 'Folklore'? Which science fiction movie popularized "May the odds be ever in your favor"? Who portrayed Captain Picard in "Star Trek: The Next Generation"? In Japan, what Christmas tradition involves couples sharing meals together, resembling Valentine's Day? What is the traditional Orthodox Easter greeting response to 'Christ is risen'?