These monsters from greek mythology are missing in titan quest:
Stymphalian Birds / Sharp feather hawks.
Nemean Lion / Tough skin Lion
Sphinx / Winged greek version.
Anteus / Earth elemental like monster that regenerates when touching earth.
Charybdis / Coral monster based boss.
Scylla / Moray eel based boss.
Siren / Female Ichtians.
Kraken / Half octopus half humanoid.
Triton / Half god of Water
Pyron / Half-god of Fire
Argus / Beholder like monster.
Ladon / 2 Headed dragon.
Echidna / Half plant (venus fly trap) half female humanoid that spawns monsters to fight for her.
Do you people have anything to add?