Fantastic Beasts: 28 Easter Eggs & References You Must See
11. The Deathly Hallows
As if he wasn't content with teasing that he's actually Grindelwald (it's obvious when you watch it back - his hair, his Dumbledore reference, the Greater Good speech...), Graves also hands over a Deathly Hallows pendant necklace to Credence Barebones to help strengthen his will to help him find the Obscurial.
This necklace is the self-same one worn by Xenophilius Lovegood in The Deathly Hallows: Part 1 when Harry, Ron and Hermione go to visit him. Fan theories linking Lovegood to Grindelwald... Go.