Slughorn is a new Hogwarts professor in "Half-Blood Prince".
The new Potions teacher is Professor Slughorn
Retired. Before his retirement he was also a Hogwarts professor.
Professor Slughorn (The headteacher when tom riddle was at hogwarts)
Slughorn was reluctant to work at Hogwarts; Harry helped Dumbledore convince Slughorn that it was in his (Slughorn's) best interest to do so - as Dumbledore had evidently foreseen. Apparently the main reason Dumbledore wanted Slughorn in Hogwarts is because Slughorn had some important information (which he really preferred to keep secret), which Harry and Dumbledore needed to defeat Lord Voldemort.Slughorn was reluctant to work at Hogwarts; Harry helped Dumbledore convince Slughorn that it was in his (Slughorn's) best interest to do so - as Dumbledore had evidently foreseen. Apparently the main reason Dumbledore wanted Slughorn in Hogwarts is because Slughorn had some important information (which he really preferred to keep secret), which Harry and Dumbledore needed to defeat Lord Voldemort.Slughorn was reluctant to work at Hogwarts; Harry helped Dumbledore convince Slughorn that it was in his (Slughorn's) best interest to do so - as Dumbledore had evidently foreseen. Apparently the main reason Dumbledore wanted Slughorn in Hogwarts is because Slughorn had some important information (which he really preferred to keep secret), which Harry and Dumbledore needed to defeat Lord Voldemort.Slughorn was reluctant to work at Hogwarts; Harry helped Dumbledore convince Slughorn that it was in his (Slughorn's) best interest to do so - as Dumbledore had evidently foreseen. Apparently the main reason Dumbledore wanted Slughorn in Hogwarts is because Slughorn had some important information (which he really preferred to keep secret), which Harry and Dumbledore needed to defeat Lord Voldemort.
No - in Harry Potter and the Deathly Hallows Snape becomes Headmaster of Hogwarts and Professor Slughorn is reinstated at Head of Slytherin.
Yes, Slughorn comes into play during the final battle at Hogwarts at the end of the book.
Horace
When the Dark Lord invaded the castle with his army, it was initially believed that Professor Slughorn had fled in cowardice; but as it transpired, had gone to Hogsmeade to round up reinforcements. He returned to the castle at the head of vast number of residents and shopkeepers from the town, along with friends and family of the students and staff already fighting. Slughorn engaged the Dark Lord head on, with McGonagall and Kingsley, proving himself a masterful duellist, able to hold his own against even the most dangerous dark wizard of all time.
Horace E. F. Slughorn returned to his previous post as Potions Master after Severus Snape was given to position of Defence Against The Dark Arts teacher in Harry Potter and the Half-Blood Prince.
Remus Lupin and Horace Slughorn both used the Hogwarts Express to travel to Hogwarts. Otherwise, the only adults on the train were the driver and the trolley lady.
He plays professor slughorn
The restricted section on Hogwarts New Zealand's password is available from the administrators (if your character will be sneaking in) or from a professor (if your character receives permission to be there).