The Slug Club was a rather exclusive society set up by Horace Slughorn as a means of collecting his favourite and most interesting pupils during his time at Hogwarts. Members were invited to dinners, drinks receptions and parties in order to mingle with each other - and Professor Slughorn. Harry Potter was inevitably immediately picked out for membership, as was Ginny Weasley, Hermione Granger, Blaise Zabini and Cormac McLaggen, for various reasons. Slughorn attracted an impressive clientele to his gatherings, including a vampire called Sanguini.