The Life and Lies of Albus Percival Wulfric Brian Dumbledore Page 19

  52. We know the gargoyle has guarded the Head’s office since at least Dippet’s time at Hogwarts, because Tom Riddle passes the gargoyle the night he frames Hagrid. (CS245)

  53. If one wants to consider Pottermore, we can go back even further, and have a potential candidate for Phineas Nigellus’s predecessor. In the Pottermore entry for Peeves, we get mention of Eupraxia Mole being Headmistress in 1876. Phineas can’t have been before her (he’d only be thirty-one in 1876), so he was Headmaster after her, and possibly directly after.

  54. This is said obliquely several times in the text, usually by Dumbledore, and Jo spelled it out in her 2005 interview with Melissa Anelli and Emerson Spartz: “His worst fear is death.” http://www.accio-quote.org/ articles/2005/0705-tlc_mugglenet-anelli-2.htm