Santorini: Hiding in the Underworld contains 17 characters:
Arachne
Cerberus
Charon
Chronus
Hades
Hecate
Hypnus
Mnemosyne
Moerae
Morpheus
Nemesis
Orpheus & Eurydice
Persephone
Phobos
Sisyphus
Tartarus
Typhon
It also contains 2 mode cards:
Nyx's Veil
Manticore's Shadow